Introduction: Early-life viral infections have been linked to both increased and decreased risk for allergic disease later in life. Causative relationships have been difficult to prove and most likely both timing and type of infection(s) are of importance. The aim was to study the association between early-life viral infections and allergy at 20 years of age. In addition, the study aimed to examine how early viral infections are associated with other known risk factors for allergy. Methods: A cohort of 281 individuals recruited before birth and categorized into three hereditary groups based on parental allergy status, defined by IgE-sensitized and allergic symptoms, was followed until age 20. Of these, 142 individuals completed both web-based questionnaires and clinical investigations. Infections were documented both as parent-reported between 0 and 2 years and seropositivity against 13 viruses at 2 years of age. Analyses included logistic regression and classification tree modeling. Results: Individuals who experienced many respiratory viral infections (11-20) during their first 2 years of life had a higher prevalence of allergies compared to their peers with fewer than 10 respiratory viral infections (58% vs. 34%, p = 0.005). Cytomegalovirus (CMV) seropositivity at 2 years of age was associated with allergy at age 20 (p = 0.026). As expected, parental allergy was also linked to the development of allergy. Conclusion: Individuals who experienced frequent respiratory viral infections during early childhood, were seropositive for CMV by age two, and had two allergic parents consistently developed allergic disease by age 20. Preventive strategies targeting early viral respiratory infections may help reduce future allergy.

AbstractBackgroundThe basophil activation test is an emerging clinical tool in the diagnosis of cow's milk allergy (CMA). The aim was to assess the association between the basophil allergen threshold sensitivity to the major milk protein casein (casein‐specific CD‐sens), the levels of milk‐ and casein‐specific Immunoglobulin E antibodies (IgE‐ab), and the severity of allergic reactions at milk challenges.MethodsWe enrolled 34 patients aged 5–15 (median 9) years who underwent a double‐blind placebo‐controlled milk‐challenge (DBPCMC) as screening before inclusion in an oral immunotherapy study for CMA. The severity of the allergic reaction at the DBPCMC was graded using Sampson's severity score. Venous blood was drawn before the DBPCMC. Milk‐ and casein‐specific IgE‐ab were analyzed. Following in vitro stimulation of basophils with casein, casein‐specific CD‐sens, was determined.ResultsThirty‐three patients completed the DBPCMC. There were strong correlations between casein‐specific CD‐sens and IgE‐ab to milk (rs = 0.682, p < .001), and between casein‐specific CD‐sens and IgE‐ab to casein (rs = 0.823, p < .001). There was a correlation between the severity of the allergic reaction and casein‐specific CD‐sens level (rs = 0.395, p = .041) and an inverse correlation between casein‐specific CD‐sens level and the cumulative dose of milk protein to which the patient reacted at the DBPCMC (rs = −0.418, p = .027). Among the 30 patients with an allergic reaction at the DBPCMC, 67% had positive casein‐specific CD‐sens, 23% had negative casein‐specific CD‐sens, and 10% were declared non‐responders.ConclusionTwo thirds of those reacting at the DBPMC had positive casein‐specific CD‐sens, but reactions also occurred despite negative casein‐specific CD‐sens. The association between casein‐specific CD‐sens and the severity of the allergic reaction and cumulative dose of milk protein, respectively, was moderate.

Introduction: Knowledge of IgE-verified allergy in young adults is limited as most studies are based on self-reported data. Allergic heredity is important in allergy development in early life, but less is known about the hereditary component later in life. The aim was to investigate IgE-verified and self-reported allergy and asthma at 20 years of age in association to parental allergy and environmental factors. Methods: In total, 281 individuals born into the cohort of well-characterized parents regarding allergic disease were followed to 20 years of age. The participants were categorized by parental allergy and examined regarding allergic diseases (IgE sensitization and allergic symptoms) at 2, 5, 10, and 20 years of age. FeNO was measured at 10 and 20 years. Results: In total, 45% of the study participants were allergic, with twice as many self-reported cases at age 20. Rhinitis was key to distinguishing confirmed allergy from self-reported. Having two allergic parents and increased FeNO were associated with an increased prevalence of allergic disease at 20 years. From a longitudinal perspective, rhinitis increased from childhood to young adulthood, in all heredity groups. Conclusion: In this longitudinal study, we have shown that two allergic parents as well as increased FeNO levels seem to be of importance for being allergic at 20 years old. Self-reported allergy was overreported - a result that should be considered in future survey-based reports on allergic diseases.

Basophils are rare granulocytes in circulation which home to tissues in a process depending on rolling, adhesion and cytokine exposure. However, it is still unclear how these steps affect basophil degranulation. Our aim was to imitate these processes associated with homing by sequential crosslinking of adhesion molecules and cytokine exposure and evaluate the effect on basophil piecemeal (PMD) and anaphylactic degranulation (AND). Blood donors with or without allergic asthma were recruited from an ongoing cohort study. Basophils were subjected to CD62L-, CD49d- or CD11b crosslinking and IL-3 or IL-33 stimulation in different orders followed by anti-IgE and fMLP stimulation. Basophil CD203c and CD63 expression were analysed by flow cytometry to determine PMD and AND, respectively. IL-3 induced PMD in basophils and combined with CD62L- or CD11b crosslinking, IL-3 potentiated the degranulation regardless of sequential order. IL-3 priming followed by adhesion molecule crosslinking induced AND and potentiated the effect of anti-IgE. CD62L- and CD11b crosslinking did not further potentiate this effect. CD49d crosslinking followed by IL-3 increased CD63 expression following anti-IgE. IL-3 potentiated the effect of fMLP on AND while adhesion molecule crosslinking did not. IL-33 had impact on PMD only when followed by adhesion molecule crosslinking but did not potentiate neither IgE-dependent nor IgE-independent degranulation. Our data indicate that sequential interactions between basophils, cytokines and adhesion molecule ligands have a decisive effect on basophil degranulation and that these interactions are operational for fine-tuning the activity of tissue dwelling basophils. These data should be considered when the effect of different pharmaceutical on basophil function is studied.

Peanut allergy is one of the major food allergies, and has an impact on the health-related quality of life (HRQoL).1 As for today there is no curative treatment, however guidelines recommend oral immunotherapy (OIT) as a therapeutic option to increase the threshold for reactions in children with persistent peanut allergy.2, 3 In line with the guidelines, measurements of treatment effect should include patient-reported outcomes such as HRQoL. Our aim was therefore to investigate if treatment with peanut OIT (pOIT) in combination with omalizumab improves self-reported HRQoL among adolescents with severe peanut allergy. The study is a part of a one-armed open phase-two study of pOIT in combination with omalizumab in severely peanut allergic adolescents (N = 23) (Figure 1, supplement 1).4 The patients received omalizumab for 8–24 weeks until vitro Basophil activation (CD-sens) to peanut stimulation was suppressed. To measure HRQoL, the food allergy questionnaire Food Allergy Quality of Life Questionnaire–Teenager Form (FAQLQ-TF) was used. Flow chart of the study design and study population (n = 11). The study population consisted of 11 (of the 23 included) patients who were able to continue with pOIT after the omalizumab treatment was stopped, and who completed the FAQLQ-TF at the start and the end of the study (Figure 1). The study participants had a mean age of 15.8 years, and the mean length of treatment with omalizumab was 93 weeks (range 46–163). The distribution of sex and co-morbidity were similar in the study population and among dropouts and treatment failures that is, participants who could not complete the treatment within scheduled time (n = 12) (supplement 2). The FAQLQ-TF mean scores significantly decreased at the end of the treatment in all domains (“Allergen avoidance and dietary restrictions”, “Emotional impact”, “Risk of accidental exposure”), and in the total score (Figure 2). To distinguish the clinical relevance of a difference, clinical minimal important difference (MID) is often used. A clinical relevance is suggested at a difference of ≥0.5 points.5 The MID at the end of the treatment in “Allergen avoidance and dietary restrictions” was 1.7 points lower than at the start, “Emotional impact” 1.6, and “Risk of accidental exposure” 1.4. In the total score, MID at the end of the treatment was 1.7. HRQoL among the study population (n = 11) at the start and at the end of the study. In adolescence, HRQoL after OIT is sparsely studied. In the present study, HRQoL improved in all domains after OIT. For the “allergen avoidance and dietary restrictions” it is interesting, since adolescence is a period in life when the individuals spend more time outside the home and need to take responsibility of making food-related decisions themselves compared to when they received help from their guardians. For the improvement in the “emotional impact”, one could speculate that after a long treatment with OIT and getting older, the adolescents got to know their disease, and feel more mature in case of an allergic reaction. Moreover, for “risk of accidental exposure” the result may reflect the increased tolerance to peanuts due to OIT, where the adolescents to a greater extent feel that they may be part of social events and even be more liberal in their diet. However, OIT is a slow and burdensome process and may need to be continued indefinitely. Therefore, benefits and downsides related to the treatment should be based on shared decision making together with the patient.6 The strength of the study includes the well characterised study population of highly sensitized peanut allergic patients with a history of anaphylactic reactions. Further, the FAQLQ-TF is valid and reliable. The main limitations are small sample size and lack of control subjects. In conclusion, the severe peanut allergic adolescents self-reported an improved HRQoL after combined treatment with pOIT and omalizumab, and the difference from start were clinically relevant. Maria Ödling and Niklas Andersson have done the statistical analyses. Maria Ödling has written the manuscript, and together with Inger Kull planned this investigation. Ann-Charlotte Sundqvist and Josef Brandström have collected the data and contributed to study design and information on the procedures. Anna Nopp and Caroline Nilsson have worked with the design of the study. All co-authors have contributed with scientific knowledge, and read and critically revised the manuscript. We thank all patients for their participation and the research staff at Forskningscentrum, Södersjukhuset. Torsten Söderbergs's Foundation, the Swedish Asthma and Allergy Association, Mjölkdroppen Foundation, Hesselman's Foundation, the Swedish order of Freemasons, Her Royal Highness Crown Princess Lovisa's research fund, Region Stockholm (ALF-project), Konsul Th C Bergh's Foundation, The Swedish Association for Allergology, and Sachs's Children and Youth Hospital. The author declares no conflicts of interest. Torsten Söderbergs’s Foundation, the Swedish Asthma and Allergy Association, Mjölkdroppen Foundation, Hesselman’s Foundation, the Swedish order of Freemasons, Her Royal Highness Crown Princess Lovisa’s research fund, Region Stockholm (ALF-project), Konsul Th C Bergh’s Foundation, The Swedish Association for Allergology, and Sachs’s Children and Youth Hospital. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The basophil activation test (BAT) has significant potential as a diagnostic tool to better phenotype and manage patients with IgE-mediated allergies, so that only a small proportion of patients need to be challenged.Sample, reagent, laboratory procedure, analysis protocols, and population characteristics can influence BAT

To the Editor, The origins of food allergy and food-related symptoms are to a large extent not understood, despite their large impact on public health.1 Our aim was to evaluate whether avoidance of intake of egg and milk during the last trimester of pregnancy compared to a high intake, associate to food reactions and IgE sensitization against egg and milk in the exposed woman's grandchildren. The KUG (Kost under graviditet, ‘Diet During Pregnancy’) study was initially an open-label randomized trial with the intervention conducted between 1983 and 1985,2 with the aim to study whether egg and milk exclusion prevent allergic disease in the offspring. The included study population were pregnant women with a history of bronchial asthma and/or rhino-conjunctivitis when exposed to animal dander and/or tree or grass pollen. They were randomized to a diet avoiding egg and milk (avoiding group) or a diet containing 1 egg and 0.5 L of milk per day (exposed group) during the last trimester of pregnancy.3, 4 Over 30 years later, 78 grandchildren were examined by a study physician, reactions to egg or milk ever were parental-reported and IgE against egg and milk measured (detailed method in Appendix S1). The avoiding group (n = 27) had 52 grandchildren and the exposed group (n = 19) 26 grandchildren, Figure 1. There were no significant differences in baseline characteristics between the grandchildren from the two exposure groups Table 1. We found a higher prevalence of reported reactions to egg among the grandchildren in the avoiding group n = 8/52 (15%) compared to the exposed group 0/26 (0%), p = .047. There was also a higher prevalence of reported reactions to egg and/or milk in the avoiding group n = 16/52 (31%) than in the exposed group n = 1/26 (3.9%) (p = .008). All participants who reported reactions to egg or milk with simultaneously elevated IgE belonged to the avoiding group, Table 1. The prevalence of atopic dermatitis was 24% in the avoiding group compared to 8% in the exposed group, although not a significant difference, however, could this suggest a higher risk in this group for food reactions. In stratified analyses, the association between avoidance of egg and milk and higher prevalence of reactions to milk or egg and/or milk was present for maternal grandmothers' grandchildren but not for paternal grandmothers' (Figure S1A,B). In the second generation, no participant in the exposed group reported reactions against egg or milk at 5 years of age (although no significant differences between the groups; Table S1). Five women from the first generation with included grandchildren did not follow the analysis per protocol, two in the avoiding group and three in the exposed group, however, not affecting the associations (Table S2). Including only the oldest child from each family did not affect the associations either (Table S3). Not all children with ever-reported reactions had IgE against egg or milk. Reasons for this could be the wide age range, where some children might have grown out of their allergy,5 and IgE only being tested in a subgroup. Others might react due to other mechanisms. The association was only present for the maternal grandmother's grandchildren, possibly suggesting epigenetic mechanisms attributed to changes in the foetal oocytes to be at play, previously seen in studies on smoking.6 In conclusion, we found the lowest prevalence of egg and milk reactions in children whose grandmother did eat a diet rich in egg and milk during the third trimester of pregnancy. Despite a limited number of participants, our results suggest diets excluding food items, especially containing allergens, to be potentially associated with food reactions in later generations. We would like to thank the late associate professor Gunnar Lilja for initiating and maintaining this cohort. We further thank all the children, parents and grandparents for contributing to this research. The Swedish Asthma and Allergy Association, F2018-0026. Ellen, Walter och Lennart Hesselmans stiftelse. EM has received personal fees from ALK, AstraZeneca, Novartis and Sanofi outside the submitted work. None of the other authors have any conflicts of interests to report. Appendix S1 Tables S1–S3 Figure S1 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A consensus protocol for the Basophil Activation Test for multicenter collaboration and External Quality AssuranceAuthors: Pascal, M# 1, Edelman SM#2, Nopp, A#3, Möbs, C4, Geilenkeuser, WJ5, Knol, EF6, Ebo, DG7, Mertens C7, Shamji, MH8, Santos, AF9,10, Patil, S11, Eberlein, B*12, Mayorga, C*13, Hoffmann HJ14*Affiliations1 Immunology Department, Centre de Diagnòstic Biomèdic, Hospital Clínic de Barcelona, Barcelona, Spain; Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Spain.2 Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland, present address Aimmune Therapeutics, Finland3 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, and Sachs´ Children and Youth Hospital, Södersjukhuset, Stockholm, Sweden4 Department of Dermatology and Allergology, Philipps-Universität Marburg, Marburg, Germany5 Reference Institute for Bioanalytics, Bonn, Germany6 Center of Translational Immunology and Dermatology/Allergology, University Medical Center Utrecht, Utrecht, The Netherlands.7 Faculty of Medicine and Health Sciences, Department of Immunology-Allergology- Rheumatology, University of Antwerp, Antwerp, Belgium8 National Heart and Lung Institute, Imperial College London, UK and NIHR Imperial Biomedical Research Centre, UK9 Department of Women and Children’s Health (Pediatric Allergy) & Peter Gorer Department of Immunobiology, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom10 Children’s Allergy Service, Evelina London Children’s Hospital, Guy’s and St Thomas’ Hospital, London, United Kingdom11 Division of Allergy and Immunology, Departments of Medicine and Pediatrics, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States12 Department of Dermatology and Allergy Biederstein, School of Medicine, Technical University Munich, Munich, Germany13 Allergy Clinical Unit, Hospital Regional Universitario de Málaga and Allergy Research Group, Instituto de Investigación Biomédica de Málaga-IBIMA-BIONAND, Malaga, Spain;14 Department of Clinical Medicine, Aarhus University, Department of Respiratory Diseases and Allergy, Aarhus University Hospital, Denmark# shared first authors, * shared senior authorsCOIM Pascal, SM Edelman, A Nopp, C Möbs, EF Knol, SU Patil and C Mayorga have no conflict of interest regarding this work. B Eberlein received methodological and technical support from the company BUEHLMANN Laboratories AG (Schönenbuch, Switzerland) outside the submitted work. Dr Hoffmann reports grant from the Innovation Fund of Denmark, outside the submitted work. Dr Shamji reports grants awarded to institution from the Immune Tolerance Network, UK Medical Research Council, Allergy Therapeuitics, LETI Laboratories, Revolo biotherapeutics and Angany Inc. He has received consulting fees from Bristol Meyers Squibb and lecture fees from Allergy Therapeutics and LETI laboratories, all outside the submitted work. Dr. Santos reports grants from Medical Research Council (MR/M008517/1; MC/PC/18052; MR/T032081/1), Food Allergy Research and Education (FARE), the NIH, Asthma UK (AUK-BC-2015-01), the Immune Tolerance Network/National Institute of Allergy and Infectious Diseases (NIAID, NIH) and the NIHR through the Biomedical Research Centre (BRC) award to Guy’s and St Thomas’ NHS Foundation Trust, during the conduct of the study; speaker or consultancy fees from Thermo Scientific, Nutricia, Infomed, Novartis, Allergy Therapeutics, IgGenix, Stallergenes, Buhlmann, as well as research support from Buhlmann and Thermo Fisher Scientific through a collaboration agreement with King’s College London, outside the submitted work. Dr Geilenkeuser is an employee of Referenizinstitut für Bioanalytik, DE that provided logistic assistance and reagent support for the study.To the editorThe basophil activation test (BAT) has significant potential as a diagnostic tool to better phenotype and manage patients with IgE-mediated allergies, so that only a small proportion of patients need to be challenged. Sample, reagent, laboratory procedure, analysis protocols, and population characteristics can influence BAT performance (1,2). Regulatory approval and clinical implementation require extensive standardization of laboratory protocols, cytometer settings, and results interpretation (3). European national authorities require External Quality Assurance (EQA) of the performance of modern diagnostic laboratories by agencies independent of test suppliers to meet ISO 15189:2012, 15189:2013 and 9001:2015.Based on an online survey among 59 responding European laboratories performing BAT in 2017 (4,5) (Online Supplement; Results of the online survey), a Task Force was launched in 2018 to create the basis for a BAT-EQA. Round Robins (RR) were organized with seven shipments of 2 donors each to 7-10 European centers with overnight courier service from Bonn, DE. To minimize variation, prior to shipment, blood basophils were activated with 1 ul FcεRI antibody/ml of blood and stabilized with 0.2 mL Transfix (Cytomark, UK) per mL of blood to stabilize activated basophils up to 48 hours for staining (6). Fresh blood was included for stimulation and staining at the participating laboratory sites.We met after the third shipment to reach consensus on a protocol for BAT (Online Supplement; Proposed SOP for in house BAT). The threshold set on an unstimulated control sample was determined empirically on an independent data set as equal or greater than 2.5% with ROC curves based on data from patients with hypersensitivity to amoxicillin and patients with peanut allergy, (Online supplement, tables S1 and S2). This proposal did not find universal consensus among the authors.Data analysis started with identification of the relevant region in a scatter plot, followed by identification of basophils with the relevant markers, for instance, using low SSC and CD193 only or CD193 and CD123. Finally, the threshold was set at 2.5% of CD63 expression on resting basophils (Figure 1A). >5% CD63+basophils above that threshold in an activated sample was considered a positive response. This setting was used to obtain the percentage of CD63+ cells in centrally preactivated and locally activated blood samples; however, it was not adopted in all labs. Data from participating labs analyzed with their proprietary and the above standardized analysis compared well (online supplement, figure S4).The first two RR were used to establish coherence between participating laboratories. Data from RR3–RR7 were comparable. The standard deviation of activation measured at all participating centers was 16.8% in preactivated blood (Figure 1B) compared with 49.2% for samples activated and analyzed locally, illustrating the utility of using preactivated blood for EQA. Shipment to Málaga took 48h, and local activation of blood basophils was consistently suboptimal, consistent with a preliminary round robin from 2012, where the clinical outcome was robust up to 24 h. Centrally activated basophils performed as well in Málaga as in other centers.EQA for BAT is critical to facilitate routine implementation of this assay in the field of in vitro allergy diagnostics. The variability of the responses to our survey highlighted the importance and need for multicenter validation. Full validation and standardization of the BAT protocol and analysis is essential and possible for setting the grounds for controlled multicenter research studies as well as EQA. The BAT-EQA Task Force provides a standard operating protocol (Online supplement; Proposed SOP for in house BAT) and reference materials for the test to standardize and enhance the accuracy of BAT for both clinical and research collaborations and EQA.

Allergic reactions, including anaphylaxis, have been reported from the second day of Pfizer- BioNTech's COVID- 19 vaccine administration in the mass vaccination programme. 1 Although the cause of these rare allergic reactions remains unclear, the excipient, polyethylene glycol (PEG), has been considered the culprit allergen. It is used as a stabilizer in the COVID- 19 mRNA vaccines from Pfizer- BioNTech, ‘Comirnaty’, and Moderna, ‘Spikevax’. A PEG- derivative polysorbate 80 is used in the adenovirus vector Oxford/AstraZeneca vaccine, ‘Vaxzevria’. 2,3 Our aim was to present our experiences of evaluat-ing 27 patients with systemic acute reactions to the first dose of COVID- 19 vaccine plus 10 patients with suspected PEG allergy di-agnosed before administration of the first vaccine dose. Our results indicate that a systemic acute reaction to the first dose, or to PEG or PEG derivatives, does not necessarily contraindicate a second dose of COVID- 19 vaccine. 4,5 Thirty- seven patients were referred to, and evaluated at, the Allergy Center in Linköping, Sweden. The study was approved by the Swedish Ethical Review Authority, Dnr 2021– 01301. Seven patients had an acute onset systemic reaction to the first dose of COVID- 19 vaccine from Oxford/AstraZeneca, Vaxzevria, one to Spikevax (Moderna) and nineteen after the Pfizer- BioNTech vaccine, Comirnaty. A second dose of Comirnaty was administered in be administered in a peaceful, professional setting where immediate resuscitation can be performed. Further studies on the underlying immunological mechanisms of the rare severe true allergic reactions to the COVID- 19 vaccines are needed.

Background: The clinical presentation of children sensitised to dog dander varies from asymptomatic to severe allergic airway disease, but the genetic mechanisms underlying these differences are not clear. The objective of the present study was to investigate nasal transcriptomic profiles associated with dog dander sensitisation in school children and to reveal clinical symptoms related with these profiles. Methods: RNA was extracted from nasal epithelial cell brushings of children sensitised to dog dander and healthy controls. Blood sample analyses included IgE against dog dander, dog allergen molecules, other airborne and food allergens, basophil activation and white blood cell counts. Clinical history of asthma and rhinitis was recorded, and lung function was assessed (spirometry, methacholine provocation and exhaled nitric oxide fraction). Results: The most overexpressed gene in children sensitised to dog dander compared to healthy controls was CST1, coding for Cystatin 1. A cluster of these children with enhanced CST1 expression showed lower forced expiratory volume in 1 s, increased bronchial hyperreactivity, pronounced eosinophilia and higher basophil allergen threshold sensitivity compared with other children sensitised to dog dander. In addition, multi-sensitisation to lipocalins was more common in this group. Conclusions: Overexpression of CST1 is associated with more severe allergic airway disease in children sensitised to dog dander. CST1 is thus a possible biomarker of the severity of allergic airway disease and a possible therapeutic target for the future treatment of airborne allergy.

BACKGROUND:Allergic reactions to food allergens usually occur after ingestion. However, fear of reactions to airborne peanut is a common concern for people with peanut allergy. There are no scientific reports on severe reactions with airborne peanut allergen.OBJECTIVE:To investigate the occurrence of allergic reactions in peanut-allergic children undergoing airborne peanut challenge and to determine levels of airborne peanut protein in a separate experimental evaluation.METHODS:Eighty-four children with peanut allergy underwent an airborne peanut challenge, 0.5 m from a bowl of peanuts for 30 min under controlled conditions. In a separate experiment, airborne peanut proteins from roasted and dry-roasted peanuts were collected at varying distances and at varying times with an electret SensAbues filter connected to an air pump. Collected airborne peanut proteins were extracted, dissolved and detected by ELISA. Basophil activation test was used to confirm biological activity.RESULTS:No moderate/severe allergic reactions to airborne peanut allergens were observed. Two children (2%) had mild rhino-conjunctivitis which required no treatment. The IgE-antibodies to peanut or Ara h 2 did not predict a reaction. In the experimental set-up, biological active peanut proteins were detected, in a very low amount, in median 166 ng/ml for dry-roasted and 33 ng/ml for roasted peanuts and decreased dramatically when the collection occurred at a greater distance (0.5-2 m) from the peanut source. Increased exposure time did affect the amount of collected peanut protein at 0 m, and the highest median was obtained after 60 min (p = .012); for time trend p = .0006.CONCLUSIONS AND CLINICAL RELEVANCE:Allergic reactions to airborne peanut proteins are rare and cannot be predicted by high levels of IgE-antibodies to peanut or Ara h 2. Only small amounts of biologically active peanut proteins were detected in the air and seem unlikely to trigger moderate/severe allergic reactions.

BACKGROUND:IgA nephropathy (IgAN) advances from multiple pathogenic "hits" resulting in poorly O-galactosylated IgA1 glycoforms (Gd-IgA1), production of antibodies and glomerular deposition of immune complexes. A sequence of immune responses arising from plasma cells, T cells and antigen presenting cells (APCs), causes glomerular injury. This study was designed to phenotype subsets of B cells, monocytes and T cells in the peripheral circulation and their association with inflammatory cytokines and kidney function in patients with IgAN, healthy controls (HC) and disease controls with autosomal dominant polycystic kidney disease (ADPKD). METHODS:Patients with IgAN (n = 13), median estimated glomerular filtration rate (eGFR) of 57 ml/min/1.73m2 (IQR 42-84), patients with ADPKD (n = 13) matched for kidney function, gender and age and gender and age-matched HC (n = 13) were recruited. CD3+ and CD3- peripheral blood mononuclear cells were isolated and profiled based on their specific surface markers for different subsets of monocytes, B and T cells and analyzed by flow cytometry. Cytokines were analyzed by ELISA. RESULTS:We observed a significant decrease in the proportion of pre-switched B cells and plasmablasts, but an increase in long-lived plasma cells in the peripheral circulation of IgAN patients compared to HC. The proportion of non-classical monocytes was significantly higher in IgAN patients compared to both HC and ADPKD. We also report an association between sCD40L levels and the proportion of pre-switched B cells, as well as sCD40L and MCP-1 levels and albuminuria in IgAN patients. CONCLUSIONS:We applied an easy-access method to analyze subsets of immune cells as well as relevant inflammatory mediators in IgAN patients. Our data demonstrate an altered B cell profile that indicates a pathophysiological role of the B cell lineage and an increased proportion of non-classical monocytes that suggests their role in the disease process.

Pediatric Allergy and ImmunologyVolume 33, Issue 1 e13682 LETTER TO THE EDITOROpen Access Transcriptome changes during peanut oral immunotherapy and omalizumab treatment Sophia Björkander, Sophia Björkander Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), ​Investigation (equal), Methodology (equal), Visualization (lead), Writing - original draft (equal), Writing - review & editing (equal)Search for more papers by this authorSimon Kebede Merid, Simon Kebede Merid orcid.org/0000-0001-5974-7676 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), Formal analysis (lead), ​Investigation (equal), Methodology (lead), Software (lead), Visualization (equal), Writing - original draft (equal), Writing - review & editing (equal)Search for more papers by this authorDavid Brodin, David Brodin Bioinformatics and Expression Core Facility, Karolinska Institutet, Huddinge, Sweden Contribution: Conceptualization (equal), Data curation (equal), Methodology (equal), Software (equal), Writing - review & editing (equal)Search for more papers by this authorJosef Brandström, Josef Brandström Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), ​Investigation (equal), Writing - review & editing (equal)Search for more papers by this authorFredrik Fagerström-Billai, Fredrik Fagerström-Billai Bioinformatics and Expression Core Facility, Karolinska Institutet, Huddinge, Sweden Contribution: Conceptualization (equal), Data curation (equal), Formal analysis (equal), Methodology (equal), Software (equal), Writing - review & editing (equal)Search for more papers by this authorMarieke van der Heiden, Marieke van der Heiden Department of Medical Microbiology and Infection Prevention, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands Contribution: Conceptualization (equal), Methodology (equal), Writing - review & editing (equal)Search for more papers by this authorJon R. Konradsen, Jon R. Konradsen Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), Writing - review & editing (equal)Search for more papers by this authorMichael Kabesch, Michael Kabesch orcid.org/0000-0003-0697-1871 Department of Pediatric Pneumology and Allergy, University Children's Hospital Regensburg (KUNO), Regensburg, Germany Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorCornelis M. van Drunen, Cornelis M. van Drunen Department of Otorhinolaryngology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorKorneliusz Golebski, Korneliusz Golebski Department of Experimental Immunology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Department of Respiratory Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Writing - review & editing (equal)Search for more papers by this authorAnke H. Maitland-van der Zee, Anke H. Maitland-van der Zee Department of Respiratory Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorUroš Potočnik, Uroš Potočnik Faculty of Medicine, Center for Human Molecular Genetics and Pharmacogenomics, University of Maribor, Maribor, Slovenia Laboratory for Biochemistry, Molecular Biology and Genomics, Faculty for Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorSusanne J. H. Vijverberg, Susanne J. H. Vijverberg orcid.org/0000-0002-4579-4081 Department of Respiratory Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorAnna Nopp, Anna Nopp Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Sachs Children and Youth Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), ​Investigation (equal), Resources (equal), Writing - review & editing (equal)Search for more papers by this authorCaroline Nilsson, Caroline Nilsson orcid.org/0000-0003-2040-8428 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Sachs Children and Youth Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Funding acquisition (equal), ​Investigation (equal), Resources (equal), Writing - review & editing (equal)Search for more papers by this authorErik Melén, Corresponding Author Erik Melén erik.melen@ki.se orcid.org/0000-0002-8248-0663 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Sachs Children and Youth Hospital, Stockholm, Sweden Correspondence Erik Melén, Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden. Email: erik.melen@ki.se Contribution: Conceptualization (equal), Data curation (equal), Funding acquisition (equal), ​Investigation (equal), Methodology (equal), Project administration (equal), Supervision (lead), Writing - original draft (equal), Writing - review & editing (equal)Search for more papers by this author Sophia Björkander, Sophia Björkander Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), ​Investigation (equal), Methodology (equal), Visualization (lead), Writing - original draft (equal), Writing - review & editing (equal)Search for more papers by this authorSimon Kebede Merid, Simon Kebede Merid orcid.org/0000-0001-5974-7676 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), Formal analysis (lead), ​Investigation (equal), Methodology (lead), Software (lead), Visualization (equal), Writing - original draft (equal), Writing - review & editing (equal)Search for more papers by this authorDavid Brodin, David Brodin Bioinformatics and Expression Core Facility, Karolinska Institutet, Huddinge, Sweden Contribution: Conceptualization (equal), Data curation (equal), Methodology (equal), Software (equal), Writing - review & editing (equal)Search for more papers by this authorJosef Brandström, Josef Brandström Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), ​Investigation (equal), Writing - review & editing (equal)Search for more papers by this authorFredrik Fagerström-Billai, Fredrik Fagerström-Billai Bioinformatics and Expression Core Facility, Karolinska Institutet, Huddinge, Sweden Contribution: Conceptualization (equal), Data curation (equal), Formal analysis (equal), Methodology (equal), Software (equal), Writing - review & editing (equal)Search for more papers by this authorMarieke van der Heiden, Marieke van der Heiden Department of Medical Microbiology and Infection Prevention, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands Contribution: Conceptualization (equal), Methodology (equal), Writing - review & editing (equal)Search for more papers by this authorJon R. Konradsen, Jon R. Konradsen Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), Writing - review & editing (equal)Search for more papers by this authorMichael Kabesch, Michael Kabesch orcid.org/0000-0003-0697-1871 Department of Pediatric Pneumology and Allergy, University Children's Hospital Regensburg (KUNO), Regensburg, Germany Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorCornelis M. van Drunen, Cornelis M. van Drunen Department of Otorhinolaryngology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorKorneliusz Golebski, Korneliusz Golebski Department of Experimental Immunology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Department of Respiratory Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Writing - review & editing (equal)Search for more papers by this authorAnke H. Maitland-van der Zee, Anke H. Maitland-van der Zee Department of Respiratory Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorUroš Potočnik, Uroš Potočnik Faculty of Medicine, Center for Human Molecular Genetics and Pharmacogenomics, University of Maribor, Maribor, Slovenia Laboratory for Biochemistry, Molecular Biology and Genomics, Faculty for Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorSusanne J. H. Vijverberg, Susanne J. H. Vijverberg orcid.org/0000-0002-4579-4081 Department of Respiratory Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands Contribution: Conceptualization (equal), Funding acquisition (equal), Writing - review & editing (equal)Search for more papers by this authorAnna Nopp, Anna Nopp Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Sachs Children and Youth Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Data curation (equal), ​Investigation (equal), Resources (equal), Writing - review & editing (equal)Search for more papers by this authorCaroline Nilsson, Caroline Nilsson orcid.org/0000-0003-2040-8428 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Sachs Children and Youth Hospital, Stockholm, Sweden Contribution: Conceptualization (equal), Funding acquisition (equal), ​Investigation (equal), Resources (equal), Writing - review & editing (equal)Search for more papers by this authorErik Melén, Corresponding Author Erik Melén erik.melen@ki.se orcid.org/0000-0002-8248-0663 Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden Sachs Children and Youth Hospital, Stockholm, Sweden Correspondence Erik Melén, Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden. Email: erik.melen@ki.se Contribution: Conceptualization (equal), Data curation (equal), Funding acquisition (equal), ​Investigation (equal), Methodology (equal), Project administration (equal), Supervision (lead), Writing - original draft (equal), Writing - review & editing (equal)Search for more papers by this author First published: 20 October 2021 https://doi.org/10.1111/pai.13682 Funding information: The PERMEABLE consortium supported by ZonMW (456008004), the Swedish Research Council (2018-05619), the Ministry of Education, Science and Sport of the Republic of Slovenia (C3330-19-252012) and the German Ministry of Education and Research (BMBF) (FKZ01KU1909A), under the frame of the ERA PerMed JTC 2018 Call. Additional funding in the Online Appendix. Sophia Björkander and Simon Kebede Merid are equal contributions. AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat To the Editor, Peanut allergy is a common food allergy and the main cause of anaphylaxis among children.1 In recent years, oral immunotherapy has emerged as a promising treatment for children with different IgE-mediated food allergies, although safety issues must be considered.2 The main aim of immunotherapy is to induce tolerance or desensitization to an allergen, which otherwise causes an allergic reaction. For oral immunotherapy, this means ingesting the allergen in a controlled manner with gradually increasing dosages. Specifically, peanut oral immunotherapy (pOIT) is able to induce tolerance/desensitization.3 While the pathogenesis of food allergy is relatively well-studied,4 mechanisms of OIT-induced tolerance are not well understood. Omalizumab (anti-IgE), which is used as treatment for severe allergic asthma and other IgE-driven allergies, can also facilitate OIT initiation5; however, little is known about the involved mechanisms, including possible changes at the transcriptional level. We therefore investigated transcriptional changes in whole blood using RNA-sequencing profiles during omalizumab treatment and pOIT in participants from the FASTX (Food Allergen Suppression Therapy with Xolair®) study previously described.5, 6 17 peanut allergic adolescents (age 12–18 years) were included in this study (Table S1). Participants were sampled at treatment start (Baseline) and were then treated with omalizumab at recommended dosages for allergic asthma for an initial 8-week period and for some participants additional periods (total of 16 or 24 weeks) until basophil activation test (BAT/CD-sens)7 analysis showed suppressed reactivity to peanut. All participants then underwent an open peanut challenge (pOIT start), before starting peanut OIT (pOIT) in combination with continued omalizumab treatment. The peanut dose was gradually increased until reaching a maintenance dose. Guided by a BAT/CD-sens after 8 weeks on the maintenance dose, participants decreased the omalizumab dose by 50% (Maintenance) and continued to decrease the dose if pOIT was tolerated. Eleven participants were able to tolerate pOIT without omalizumab for >8 weeks and then passed an open peanut food challenge (Final); six participants could not discontinue omalizumab; however, blood samples were obtained after 2–3 years on omalizumab (Final); six participants dropped out of the study (Figure S1). RNA-sequencing was performed on whole blood (n = 17) at Baseline, pOIT start, Maintenance and Final timepoints using the NovaSeq 6000 platform. DESeq2 was used for differential expression analysis of the omalizumab effect and a linear mixed-effect model for analyses during pOIT in combination with omalizumab (pOIT + O) after adjustment for treatment outcome and cell types estimates via deconvolution (Figure S2). For further details on the treatment protocol, methods and statistical analysis, see the Online Appendix and Table S1. For study participant characteristics at Baseline, see Table S1. To elucidate whether omalizumab treatment alone induced alterations in peripheral blood gene expression, we investigated the two first timepoints, Baseline and pOIT start; however, no significant differences were observed (Figure S3). In the longitudinal analysis (pOIT start to Final), 680 genes associated with pOIT + O at nominal p < .005 (Table S2). The Gene Ontology (GO) biological process of these 680 genes is presented in Figure 1A,B. Upregulation of 337 genes was linked to GO terms ‘protein regulation and modification’, while ‘neutrophil degranulation, immune response, phagocytosis and metabolic process’ were among the top terms for the 343 downregulated genes. Out of the 680 genes, 16 were differentially expressed at false discovery rate (FDR) adjusted p < .05 (Table 1, Figure S4). The three genes with the largest negative and positive coefficients, respectively, are displayed in Figure 1C,D; downregulation of ASGR2, GPBAR1 and HM13, and upregulation of USP44, ICOS and CDKN2AIP. Finally, we evaluated the overlap between our 680 pOIT + O-associated genes and peripheral blood gene expression changes associated with acute peanut allergic reactions in a recently published clinical study by Watson et al using the same p-value cut-off (p < .005).8 Out of our 680 significant genes, 108 genes overlapped with differentially expressed genes found by Watson et al,8 mostly with opposite direction, Penrichment = 0.0095 (Figure 2). FIGURE 1Open in figure viewerPowerPoint (A, B) Gene ontology (GO) biological process analysis of upregulated (A) and downregulated (B) genes. The x-axis shows the gene ratio of the overlapping genes of our gene list with the pathway gene set. The colour bar represents the adjusted p-value, and the circle size is the count of overlapping genes. (C, D) Boxplots display log2 expression values for six pOIT genes (C: upregulated, D: downregulated) throughout the treatment protocol at FDR p < .05. Red box: pOIT start, green box: Maintenance, blue box: Final. ORA = Over-representation analysis TABLE 1. FDR significant pOIT + O-related genes Gene name Full name Ensembl.ID Coefficient Standard error p-value FDR ASGR2 Asialoglycoprotein Receptor 2 ENSG00000161944 −0.3908 0.0809 4.68 × 10−05 0.0496 GPBAR1 G Protein-Coupled Bile Acid Receptor 1 ENSG00000179921 −0.3264 0.0656 3.21 × 10−05 0.0453 HM13 Minor Histocompatibility antigen H13 ENSG00000101294 −0.2385 0.0461 1.81 × 10−05 0.0414 CALR Calreticulin ENSG00000179218 −0.2120 0.0370 3.67 × 10−06 0.0386 RASSF4 Ras Association Domain Family Member 4 ENSG00000107551 −0.1865 0.0370 2.87 × 10−05 0.0453 CFL1 Cofilin 1 ENSG00000172757 −0.1859 0.0331 5.85 × 10−06 0.0386 KDELR1 KDEL Endoplasmic Reticulum Retention Protein Receptor 1 ENSG00000105438 −0.1680 0.0300 6.83 × 10−06 0.0386 YWHAE Tyrosine 3-Monooxygenase/Tryptophan 5-Monooxygenase Activation Protein Epsilon ENSG00000108953 −0.1576 0.0296 1.19 × 10−05 0.0414 USP44 Ubiquitin Specific Peptidase 44 ENSG00000136014 1.0998 0.2224 3.48 × 10−05 0.0454 ICOS Inducible T-Cell Costimulator ENSG00000163600 0.4596 0.0957 4.69 × 10−05 0.0496 CDKN2AIP Cyclin-dependent Kinase Inhibitor 2A Interacting Protein ENSG00000168564 0.3603 0.0705 2.27 × 10−05 0.0428 ATM ATM Serine/Threonine Kinase ENSG00000149311 0.2913 0.0563 1.95 × 10−05 0.0414 ADD3 Adducin 3 ENSG00000148700 0.2619 0.0524 3.18 × 10−05 0.0453 GNG2 G Protein Subunit Gamma 2 ENSG00000186469 0.2436 0.0497 4.01 × 10−05 0.0486 SEPTIN11 Septin 11 ENSG00000138758 0.1897 0.0358 1.47 × 10−05 0.0414 OGT O-Linked N-Acetylglucosamine (GlcNAc) Transferase ENSG00000147162 0.1859 0.0354 1.56 × 10−05 0.0414 FIGURE 2Open in figure viewerPowerPoint Overlap of 108 genes from the FASTX pOIT study with the peanut-related genes found in Watson et al. at nominal p < .005. The y-axis represents changes in gene expression between the means at baseline and the 4-h time point of the peanut challenge in Watson et al, and the x-axis is effect size estimates from the mixed-effect model in the FASTX pOIT study. The green colour shows opposite direction, and the pink same direction Our results demonstrate that omalizumab treatment alone does not induce alterations in whole blood gene expression in patients with severe food allergy. This is not surprising given that these patients were unexposed to peanut allergen at the time of Baseline blood sampling, and any concomitant asthma, rhinitis or eczema were well controlled. However, since omalizumab can facilitate OIT, this drug likely allows for biological changes related to allergen tolerance during OIT. Our longitudinal analysis during pOIT + O identified up- and downregulation of several immune-related genes. CD278/ICOS (Inducible T-cell costimulatory) is expressed on activated T cells and appears to play a role in directing effector T-cell differentiation and responses during inflammatory conditions.9 ICOS expression on T regulatory cells and T follicular helper cells may be involved in the allergic disease mechanism.10 In the pathway analyses, we observed significant enrichment for several GO biological process terms related to T-cell function and immune responses. Notably, we have previously described alterations in T-cell polyclonal in vitro activation during pOIT + O in the FASTX study,11 and our cell fraction analyses also identified immunological changes (Figure S2). Comparing our findings with data described by Watson et al8 suggests that pOIT + O may alter the expression level of genes that were found affected during an acute peanut allergic reaction. The main limitations of this study are small sample size and lack of control subjects without omalizumab treatment, which may mask changes only associated with pOIT. Further, whole blood contains a highly heterogeneous cell population, which can only be partly accounted for by estimated cell fractions and our analysis may have failed to detect important treatment-related changes connected specifically to peanut antigen-specific cells. In conclusion, omalizumab treatment alone does not alter the transcriptional signature in peripheral blood of peanut allergic patients, but during pOIT + O, several immune-related signatures were observed. These results may provide insights into mechanisms of allergen tolerance. ACKNOWLEDGEMENTS We thank all FASTX patients for their participation and the research staff at Forskningscentrum, Södersjukhuset. CONFLICT OF INTEREST None. AUTHOR CONTRIBUTIONS Sophia Björkander: Conceptualization (equal); data curation (equal); investigation (equal); methodology (equal); visualization (lead); writing–original draft (equal); writing–review and editing (equal). Simon Kebede Merid: Conceptualization (equal); data curation (equal); formal analysis (lead); investigation (equal); methodology (lead); software (lead); visualization (equal); writing–original draft (equal); writing–review and editing (equal). David Brodin: Conceptualization (equal); data curation (equal); methodology (equal); software (equal); writing–review and editing (equal). Josef Brandström: Conceptualization (equal); data curation (equal); investigation (equal); writing–review and editing (equal). Fredrik Fagerström-Billai: Conceptualization (equal); data curation (equal); formal analysis (equal); methodology (equal); software (equal); writing–review and editing (equal). Marieke van der Heiden: Conceptualization (equal); methodology (equal); writing–review and editing (equal). Jon R. Konradsen: Conceptualization (equal); data curation (equal); writing–review and editing (equal). Michael Kabesch: Conceptualization (equal); funding acquisition (equal); writing–review and editing (equal). Cornelis M. van Drunen: Conceptualization (equal); funding acquisition (equal); writing–review and editing (equal). Korneliusz Golebski: Conceptualization (equal); writing–review and editing (equal). Anke H. Maitland-van der Zee: Conceptualization (equal); funding acquisition (equal); writing–review and editing (equal). Uroš Potočnik: Conceptualization (equal); funding acquisition (equal); writing–review and editing (equal). Susanne J. H. Vijverberg: Conceptualization (equal); funding acquisition (equal); writing–review and editing (equal). Anna Nopp: Conceptualization (equal); data curation (equal); investigation (equal); resources (equal); writing–review and editing (equal). Caroline Nilsson: Conceptualization (equal); funding acquisition (equal); investigation (equal); resources (equal); writing–review and editing (equal). Erik Melén: Conceptualization (equal); data curation (equal); funding acquisition (equal); investigation (equal); methodology (equal); project administration (equal); supervision (lead); writing–original draft (equal); writing–review and editing (equal). ETHICAL APPROVAL The study was approved by the Ethics Committee in Stockholm: 2013/827-31/3, 2014/1980-32, 2016/1390-32, 2020–00807 and the Swedish Drug Agency: 5.1–2013–46183; the trial is registered at EudraCT: 2012–005625–78, ClinicalTrails.gov; NCT02402231. Patients and caregivers provided written informed consent. PEER REVIEW The peer review history for this article is available at https://publons.com/publon/10.1111/pai.13682. Open Research PEER REVIEW The peer review history for this article is available at https://publons.com/publon/10.1111/pai.13682. Supporting Information Filename Description pai13682-sup-0001-FigS1.pdfPDF document, 67.6 KB Fig S1 pai13682-sup-0002-FigS2.tifTIFF image, 826.4 KB Fig S2 pai13682-sup-0003-FigS3.tifTIFF image, 320 KB Fig S3 pai13682-sup-0004-FigS4.tifTIFF image, 1.6 MB Fig S4 pai13682-sup-0005-TableS1.docxWord 2007 document , 41.7 KB Online Appendix and Table S1 pai13682-sup-0006-TableS2.xlsxapplication/excel, 58.9 KB Table S2 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. REFERENCES 1Vetander M, Protudjer JLP, Lilja G, et al. Anaphylaxis to foods in a population of adolescents: incidence, characteristics and associated risks. Clin Exp Allergy. 2016; 46: 1575- 1587. https://doi.org/10.1111/cea.12842Wiley Online LibraryCASPubMedWeb of Science®Google Scholar 2Chu DK, Wood RA, French S, et al. Oral immunotherapy for peanut allergy (PACE): a systematic review and meta-analysis of efficacy and safety. Lancet. 2019; 393: 2222- 2232. https://doi.org/10.1016/S0140-6736(19)30420-9CrossrefCASPubMedWeb of Science®Google Scholar 3Fiocchi A, Artesani MC, Fierro V, et al. Oral immunotherapy for peanut allergy: the con argument. World Allergy Organ J. 2020; 13: 100445. https://doi.org/10.1016/j.waojou.2020.100445CrossrefPubMedGoogle Scholar 4Ramsey N, Berin MC. Pathogenesis of IgE-mediated food allergy and implications for future immunotherapeutics. Pediatr Allergy Immunol. 2021; 32(7): 1416- 1425. https://doi.org/10.1111/pai.13501Wiley Online LibraryCASPubMedWeb of Science®Google Scholar 5Brandström J, Vetander M, Sundqvist A-C, et al. Individually dosed omalizumab facilitates peanut oral immunotherapy in peanut allergic adolescents. Clin Exp Allergy. 2019; 49: 1328- 1341. https://doi.org/10.1111/cea.13469Wiley Online LibraryPubMedWeb of Science®Google Scholar 6Brandström J, Vetander M, Lilja G, et al. Individually dosed omalizumab: an effective treatment for severe peanut allergy. Clin Exp Allergy. 2017; 47: 540- 550. https://doi.org/10.1111/cea.12862Wiley Online LibraryCASPubMedWeb of Science®Google Scholar 7Nopp A, Cardell LO, Johansson SG, Oman H. CD-sens: a biological measure of immunological changes stimulated by ASIT. Allergy. 2009; 64: 811- 814. https://doi.org/10.1111/j.1398-9995.2008.01900.xWiley Online LibraryCASPubMedWeb of Science®Google Scholar 8Watson CT, Cohain AT, Griffin RS, et al. Integrative transcriptomic analysis reveals key drivers of acute peanut allergic reactions. Nat Commun. 2017; 8: 1943. https://doi.org/10.1038/s41467-017-02188-7CrossrefCASPubMedWeb of Science®Google Scholar 9Wikenheiser DJ, Stumhofer JS. ICOS co-stimulation: friend or foe? Front Immunol. 2016; 7. https://doi.org/10.3389/fimmu.2016.00304CrossrefPubMedWeb of Science®Google Scholar 10Li DY, Xiong XZ. ICOS(+) tregs: a functional subset of tregs in immune diseases. Front Immunol. 2020; 11: 2104. https://doi.org/10.3389/fimmu.2020.02104CrossrefCASPubMedWeb of Science®Google Scholar 11Heiden M, Nopp A, Brandström J, et al. A pilot study towards the immunological effects of omalizumab treatment used to facilitate oral immunotherapy in peanut-allergic adolescents. Scand J Immunol. 2021; 93:e13005. https://doi.org/10.1111/sji.13005Wiley Online LibraryPubMedWeb of Science®Google Scholar Volume33, Issue1January 2022e13682 FiguresReferencesRelatedInformation

We must compliment Hamilton et al1Hamilton R.G. Hemmer W. Nopp A. Kleine-Tebbe J. Advances in IgE testing for diagnosis of allergic disease.J Allergy Clin Immunol Pract. 2020; 8: 2495-2504Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar on their review of advances in allergy diagnostic testing. We would like to offer an update in response to the authors' concerns about Allergy Diagnostic Practice Parameters and clarify how the Joint Task Force on Practice Parameters (JTFPP) is evolving to serve the needs of the practicing allergist-immunologist.2AAAAI/ACAAI Joint Task Force on Practice Parameters.http://allergyparameters.orgGoogle Scholar The JTFPP is fully engaged in producing not only focused Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines but also full-spectrum traditional practice parameters.2AAAAI/ACAAI Joint Task Force on Practice Parameters.http://allergyparameters.orgGoogle Scholar, 3Shaker M.S. Oppenheimer J. Wallace D.V. Golden D.B.K. Lang D.M. Joint Task Force for Allergy Practice Parameters, et al. Making the GRADE in anaphylaxis management: toward recommendations integrating values, preferences, context, and shared decision making.Ann Allergy Asthma Immunol. 2020; 124: 526-535.e2Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar, 4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar More than 5 years ago, advancements in evidence-based medicine (EBM) led the American Academy of Allergy, Asthma, and Immunology (AAAAI), the American College of Allergy, Asthma, and Immunology (ACAAI), and JTFPP to re-focus selected guidelines using the GRADE method.3Shaker M.S. Oppenheimer J. Wallace D.V. Golden D.B.K. Lang D.M. Joint Task Force for Allergy Practice Parameters, et al. Making the GRADE in anaphylaxis management: toward recommendations integrating values, preferences, context, and shared decision making.Ann Allergy Asthma Immunol. 2020; 124: 526-535.e2Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar, 4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar, 5Instute of Medicine (US)Committe on Standards for Developing Trustworthy Clinical Practice Guidelines. National Academies Press (US). Clinical practice guidelines we can trust.2011https://www.ncbi.nlm.nih.gov/books/NBK209539/Google Scholar This was for good reason. The Institute of Medicine recommendations for the EBM approach to guidelines had led developers to more carefully evaluate not only the type of evidence (eg, randomized controlled trial [RCT] vs observational) but also the certainty of that evidence (including imprecision, inconsistency, and indirectness), and the risk of bias that can be present even in large RCTs.3Shaker M.S. Oppenheimer J. Wallace D.V. Golden D.B.K. Lang D.M. Joint Task Force for Allergy Practice Parameters, et al. Making the GRADE in anaphylaxis management: toward recommendations integrating values, preferences, context, and shared decision making.Ann Allergy Asthma Immunol. 2020; 124: 526-535.e2Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar, 4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar, 5Instute of Medicine (US)Committe on Standards for Developing Trustworthy Clinical Practice Guidelines. National Academies Press (US). Clinical practice guidelines we can trust.2011https://www.ncbi.nlm.nih.gov/books/NBK209539/Google Scholar In addition to a rigorous evaluation of evidence, the GRADE approach incorporates a broad societal perspective that considers the balance of effects, benefits, burdens, harms, equity, acceptability, feasibility, and cost.3Shaker M.S. Oppenheimer J. Wallace D.V. Golden D.B.K. Lang D.M. Joint Task Force for Allergy Practice Parameters, et al. Making the GRADE in anaphylaxis management: toward recommendations integrating values, preferences, context, and shared decision making.Ann Allergy Asthma Immunol. 2020; 124: 526-535.e2Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar,4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar GRADE guidelines begin with systematic reviews and meta-analyses, and then apply a comprehensive assessment of evidence certainty, while also adopting a nuanced understanding of values, preferences, and context to transparently deliver recommendations to guide clinical practice.3Shaker M.S. Oppenheimer J. Wallace D.V. Golden D.B.K. Lang D.M. Joint Task Force for Allergy Practice Parameters, et al. Making the GRADE in anaphylaxis management: toward recommendations integrating values, preferences, context, and shared decision making.Ann Allergy Asthma Immunol. 2020; 124: 526-535.e2Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar,4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar More than 110 organizations from 19 countries have endorsed GRADE, including the Centers for Disease Control and Prevention, the Agency for Health Research and Quality, the American College of Physicians, and UpToDate.4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar,6Agency for Healthcare Research and QualityGuidelines and measures.https://www.ahrq.gov/gam/index.htmlGoogle Scholar In addition to evolving with the standard of guideline development, the JTFPP, AAAAI, and ACAAI realized that GRADE was a requirement for inclusion of guidelines in the National Guideline Clearinghouse, which made them more likely to be considered by third-party payors and policymakers.6Agency for Healthcare Research and QualityGuidelines and measures.https://www.ahrq.gov/gam/index.htmlGoogle Scholar In this environment, the JTFPP leveraged skills and resources to apply GRADE methodology to specific allergy-immunology practice parameters.2AAAAI/ACAAI Joint Task Force on Practice Parameters.http://allergyparameters.orgGoogle Scholar This led to the publication of the first JTFPP GRADE guideline in 2017, and subsequent development and publication of multiple GRADE guidelines including anaphylaxis, eosinophilic esophagitis, and peanut allergy diagnosis.2AAAAI/ACAAI Joint Task Force on Practice Parameters.http://allergyparameters.orgGoogle Scholar Importantly, the core principles of GRADE have always applied to JTFPP practice parameters. The need to carefully evaluate evidence and incorporate the perspective of both patients and clinicians is not new. Although the standards and transparency of evaluations have evolved,4GRADE Working Group.http://www.gradeworkinggroup.org/Google Scholar,6Agency for Healthcare Research and QualityGuidelines and measures.https://www.ahrq.gov/gam/index.htmlGoogle Scholar the JTFPP continues to apply these same principles to traditional practice parameters for the clinical practice of allergy-immunology. Although GRADE parameters provide a highly granular evaluation of targeted questions key to the specialty, traditional practice parameters continue to inform broad topic areas and often include the results of more targeted GRADE analyses. For example, the 2020 Rhinitis Traditional Parameter extended recommendations of the previously published 2017 Rhinitis GRADE Guideline.2AAAAI/ACAAI Joint Task Force on Practice Parameters.http://allergyparameters.orgGoogle Scholar At any point in time, the JTFPP is actively developing 2 GRADE guidelines and 2 traditional practice parameters simultaneously.2AAAAI/ACAAI Joint Task Force on Practice Parameters.http://allergyparameters.orgGoogle Scholar We are grateful to the dedicated individuals of the JTFPP and guideline workgroups who have volunteered countless hours to produce practice parameters for the specialty, to the AAAAI and ACAAI, and to the members of these premier professional societies for their support. In our practices, laboratories, journals, and societies, each allergist-immunologist continues the work to improve the health care we deliver to patients every day. Hamilton et al1Hamilton R.G. Hemmer W. Nopp A. Kleine-Tebbe J. Advances in IgE testing for diagnosis of allergic disease.J Allergy Clin Immunol Pract. 2020; 8: 2495-2504Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar make clear the need to further understand the clinical application of the rapid advancements in our field to support and inform the development of guidelines, and improve the health of patients and populations alike. Advances in IgE Testing for Diagnosis of Allergic DiseaseThe Journal of Allergy and Clinical Immunology: In PracticeVol. 8Issue 8PreviewSince its discovery in 1967, IgE antibody detection in skin and blood has identified a state of allergic sensitization and served as a necessary but not sufficient risk factor that requires objective symptoms to make the definitive diagnosis of human allergic disease. More recently, quantitative IgE antibody levels in serum against allergenic extracts, molecules, and epitopes have pushed its application into more accurately identifying the specificity of the allergic response for targeting immunotherapy, predicting allergic symptom severity after allergen exposure, and attempting to distinguish tolerance from food allergy. Full-Text PDF Reply to "Developing practice parameters that improve health of patients and populations"The Journal of Allergy and Clinical Immunology: In PracticeVol. 9Issue 2PreviewThe authors thank Golden and Shaker1 for their update regarding the development of allergy specialty–related practice parameters and comments as they relate to utility of diagnostic method delimited practice parameters such as the classic Bernstein et al report2 that we discussed in our review on diagnostic allergy methods.3 We appreciate their work on the Joint Task Force on Practice Parameters, which has been involved in preparing evidence-based guidelines for the allergy community using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method that considers the type and certainty of evidence. Full-Text PDF

Peanut allergy is a common food allergy and the main cause of anaphylaxis among children. Peanut oral immunotherapy (pOIT) can lead to desensitization, and combined treatment with omalizumab may facilitate OIT initiation. Still, mechanisms of tolerance are not well understood. We therefore investigated transcriptional changes using RNA-seq profiles during omalizumab treatment and pOIT. Peanut-allergic adolescents (n=17, age 12-19 years) were included and treated with omalizumab for 8 weeks followed by a step‐wise increase of daily peanut ingestion, and subsequent withdrawal of omalizumab. Finally, an open peanut challenge was performed. RNA-sequencing was performed on peripheral blood cells collected before and 3 times during pOIT (max. pOIT treatment duration 2.5 years) using the NovaSeq 6000 platform. DESeq2 was used for differential expression analysis of the omalizumab effect and a linear mixed-effect model for analyses during pOIT after adjustment for covariates and cell type. No differentially expressed genes were observed in relation to omalizumab treatment. However, the longitudinal analysis of pOIT identified 16 differentially expressed genes at FDR-adjusted P<0.05. We observed significant upregulation of USP44 and ICOS and down-regulation of ASGR2, GPBAR1 and HM13 during pOIT. GO biological process analysis (440 genes, FDR<0.1) revealed enrichment of T cell differentiation and activation (upregulated genes), as well as leukocyte mediated immunity and neutrophil degranulation (downregulated genes). In conclusion, assessment of transcriptional changes following omalizumab treatment and pOIT in peanut allergy patients provides insights into mechanisms of allergen tolerance.

Anti‐IgE treatments, such as omalizumab, have shown promising effects in allergy treatment. Our previous work has shown that individualized omalizumab treatment (OT) allows a safe initiation and rapid up‐dosing of peanut oral immunotherapy (OIT) in peanut‐allergic adolescents. However, the broader immunological effects of this OT are incompletely understood. In this pilot study, we longitudinally followed the total B‐ and T‐cell immunity during OT, using flow cytometry, ELISpot and ELISA. Peripheral blood mononuclear cells (PBMCs) and plasma were collected from participants (n = 17) at several timepoints during treatment, before starting OT (baseline), prior to starting OIT during OT (start OIT) and at maintenance dose OIT prior to OT reduction (maintenance). OT did not affect the total B‐cell compartment over treatment time, but our results suggest an association between the OT dosage scheme and the B‐cell compartment. Further, in vitro polyclonal T‐cell activation at the different timepoints suggests a cytokine skewing towards the Th1 phenotype at the expense of Th2‐ and Th9‐related cytokines during treatment. No differences in the frequencies or phenotype of regulatory T cells (Tregs) over treatment time were observed. Finally, plasma chemokine levels were stable over treatment time, but suggest elevated gut homing immune responses in treatment successes during the treatment as compared to treatment failures. The novel and explorative results of this pilot study help to improve our understanding on the immunological effects of OT used to facilitate OIT and provide guidance for future immunological investigation in large clinical trials.