The adaptors DOCK8 and MyD88 have been linked to serological memory. Here we report that DOCK8-deficient patients had impaired antibody responses and considerably fewer CD27(+) memory B cells. B cell proliferation and immunoglobulin production driven by Toll-like receptor 9 (TLR9) were considerably lower in DOCK8-deficient B cells, but those driven by the costimulatory molecule CD40 were not. In contrast, TLR9-driven expression of AICDA (which encodes the cytidine deaminase AID), the immunoglobulin receptor CD23 and the costimulatory molecule CD86 and activation of the transcription factor NF-κB, the kinase p38 and the GTPase Rac1 were intact. DOCK8 associated constitutively with MyD88 and the tyrosine kinase Pyk2 in normal B cells. After ligation of TLR9, DOCK8 became tyrosine-phosphorylated by Pyk2, bound the Src-family kinase Lyn and linked TLR9 to a Src-kinase Syk-transcription factor STAT3 cascade essential for TLR9-driven B cell proliferation and differentiation. Thus, DOCK8 functions as an adaptor in a TLR9-MyD88 signaling pathway in B cells.

BACKGROUND: The immunomodulatory effects of vitamin B12 deficiency in children have not yet been established in the literature. In the current study, the effects of vitamin B12 on the immune system in asymptomatic and otherwise healthy infants have been studied. METHODS: The study was conducted at Marmara University, "well-child" outpatient clinic. Vitamin B12 level was measured in a cohort of 611 healthy term infants, followed regularly for at least 6 months. Immunoglobulin measurements, lymphocyte subset analysis, cytokine production analysis, lymphocyte proliferation assays and evaluation of lymphocyte apoptosis were performed in a subset of 60 infants. RESULTS: In this cohort, one out of three babies displayed vitamin B12 deficiency. The percentage of CD4+CD25+ regulatory T cells (Tregs) was lower in vitamin B12 deficient babies than in controls. Although the percentage of Tregs increased after treatment, the change was not significant. There was no difference of cytokine levels between vitamin B12 deficient and control groups. However, proinflammatory cytokines were reduced after treatment. No significant difference was observed for immunoglobulins, early apoptosis and lymphocyte proliferation. CONCLUSIONS: Vitamin B12 deficiency is an underestimated health problem among the developing countries. The clinical consequences of the decreased percentage of Tregs associated with vitamin B12 deficiency, and reduction of proinflammatory cytokines after vitamin supplementation needs to be further studied, especially in terms of emerging allergies, autoimmune disorders and anti-inflammatory effects.

Primary immune deficiencies (PID) are known to be more than 400 genetic defects caused by the impairment in development and/or functions of the immune system. Common Variable Immunodeficiency (CVID), Ataxia Telangiectasia (AT) and Agammaglobulinemia (AG) are examples of the most common immunodeficiency syndrome. Natural killer (NK) cells are a component of innate immune system and play a major role in the host-rejection of both tumors and virally infected cells. iNKT cells have a role in autoimmune and infectious diseases and controlling of tumor rejection. In this study, NK and iNKT cells and their functions, and intracellular cytokine amount are aimed to determine in patients that suffer CVID, AT and AG. NKp30, NKp46, NKG2D, perforin and granzyme mRNA expression levels were analyzed using RT-PCR. Receptors, cytokine amount of NK cell subset and iNKT were analyzed by flow cytometry. Decreased CD3+ T and elevated NK cell subset in pediatric AT were found. Expression of NKp44 was decreased in adult AG, but not in pediatric patients. Low NKp44 expression in CD3-CD16+CD56dim NK cell subset was found in pediatric AT patients. High HLA-DR, perforin and granzyme expression were found in CD3-CD16+CD56dim NK cell subset of pediatric CVID and AT patients. Alteration of the number of NK subsets, NK receptor expression and cytokine production were observed in pediatric patients compared to healthy subjects.

Elucidating the molecular basis of immunodeficiency diseases is a powerful approach to discovering new immunoregulatory pathways in humans. Here we report 10 affected individuals from 4 families with a new immunodeficiency disease comprising of severe progressive lymphopenia, autoimmunity, immunodeficiency, and liver disease due to recessive loss of function variants in “GTPase of immunity-associated proteins” protein 5 (GIMAP5). We show that the disease involves the progressive loss of naïve T lymphocytes and a corresponding increase in antigen-experienced, but poorly functional and replicatively senescent T cells. In vivo treatment of Gimap5-deficient mice with rapamycin (an inhibitor of mTORC1) significantly restores the fraction of naïve T lymphocytes. Furthermore, a GIMAP5-deficient human patient who was treated with rapamycin (sirolimus) showed a remarkable reduction in spleen/lymph node size. Together, these observations reveal that GIMAP5 plays a critical role in lymphocyte metabolism which is essential for senescence prevention and immune competence, suggesting that an inhibitor of mTORC1 could be a valuable clinical intervention in treating patients deficient for GIMAP5.

Loss and gain-of-function (GOF) mutations in human signal transducer and activator of transcription 1 (STAT1) lead to distinct phenotypes. Although recurrent infections are common to both types of STAT1 mutations, GOF mutations are distinguished by chronic mucocutaneous candidiasis and autoimmunity. However, the clinical spectra of STAT1 GOF mutations continue to expand. We here describe two patients with STAT1 GOF mutations presenting early in life with combined immunodeficiency (CID).

The Nijmegen Breakage syndrome (NBS) is characterized by chromosomal instability, combined immunodeficiency, and distinctive physical features. We present two siblings with NBS presenting with strikingly different manifestations. The proband is a 6-year-old female with short stature, microcephaly, hepatosplenomegaly, rectovaginal fistula, anal atresia, an ectopic kidney, recurrent fevers and otitis media. A 7-year-old brother has developmental delay, failure to thrive, and microcephaly without recurring infections. Both patients have hypogammaglobulinemia, B cell lymphopenia and reduced phytohaemagglutinin-induced lymphocyte proliferation. Both siblings are homozygous for the c.657_661delACAAA (p.Lys219Asnfs*16) mutation in the NBN (NBS1) gene.

AIMImmunoglobulin replacement therapy is required to reduce the frequency and severity of infections in patients with primary antibody deficiencies. Immunoglobulin G (IgG) can be administered intramuscularly, intravenously or subcutaneously. We aimed to evaluate the efficacy, dose adjustment and adverse events in subcutaneous immunoglobulin therapy by retrospectively presenting the records of 16 patients who received subcutaneous immunoglobulin therapy.MATERIAL AND METHODSThe demographic findings, clinical and laboratory findings, subcutaneous immunoglobulin dosage and dose frequency, infusion time, area and methods, adverse events and frequency of infections were obtained from patient files and recorded.RESULTSSixteen patients (seven female, nine male) aged between 0-33 years who were diagnosed with primary immune deficiency and treated with subcutaneous immunoglobulin were enrolled. All patients had been receiving intravenous imunoglobulin (5-10%) at a dose of 0.33-1.25 gr/kg/dose with two-four week intervals before subcutaneous immunoglobulin. Subcutaneous immunoglobulin (10%) was administered at a dose of 0.03-0.43 gr/kg/dose with one-two week intervals. No significant difference was found between serum through IgG levels before administration of intravenous imunoglobulin and steady state IgG levels during subcutaneous immunoglobulin therapy. When five patients whose serum through IgG levels were below 600 mg/dL were evaluated, however, a significant increase was found in steady state IgG levels with subcutaneous immunoglobulin therapy (p=0.043). In a ten-month follow-up period, seven infections were observed in four patients (three upper respiratory infectons, two lower respiratory tract infections and three acute gastroenteritis). No acute severe bacterial infection was observed. Local advers reaction was reported in only 10 of 180 infusions (6%). No serious adverse events were reported. All 16 patients were willing to continue IgG replacement therapy by subcutaneous administration.CONCLUSIONSIg replacement therapy by subcutaneous route is an efficient, safe and easy option which is eligible for individual administration. Home therapy is feasible for patients with primary immune deficiency, if informed consent is obtained and sufficient education is ensured.

Atopic dermatitis (AD) is a heterogeneous disease with regard to clinical phenotype and natural history. We investigated T cell subtypes and cytokine responses in peripheral blood and skin lesions of AD patients with various sensitivities. Immunological studies were performed in 27 subjects: 9 house dust mite (HDM)-sensitized; 6 subjects with sensitizations other than HDM; 7 non-allergic AD patients and 5 healthy controls. Among those, skin biopsy samples of 13 subjects were evaluated for immunohistochemical analyses, as well. The mean age was 8.93±5.17 years. HDM-allergic AD emerged as a distinct immunologic phenotype, with higher production of interleukin (IL)-4, -5, -2 both at rest and when stimulated by Der p1 or SEB along with higher Th17. As for TH17 cell percentage, it was increased in all AD groups compared to healthy controls, while HDM-allergic group was distinguished with a significantly lower production of IL-17. Patients with sensitizations other than HDM were mostly similar to non-allergic AD, with increased Th17 and CD4+CD69+interferon-gamma (IFN-γ)+ T cells percentage. The biopsy of lesional skin showed that HDM-allergic AD had lower IFN-γ and IFN-γ co-expressing CD8+ T cells compared to patients with other sensitizations (p=0.03 and p=0.04, respectively). Among the HDM allergic patients, pairwise comparison of lesional versus non-lesional skin revealed higher CD4+ T cells numbers, expression of forkhead box P3 (Foxp3) and T-cell-specific transcription factor (T-bet) (p=0.018, p=0.018, p=0.018, respectively). HDM-allergic AD is a distinct subtype with a predominant skewing in Th2 and higher Th17 cell percentage along with a blunted Th1 response in the skin, all of which may have therapeutic implications.

Antiphospholipid syndrome (APS) is a disease characterized by recurrent arterial and venous thromboses. Rapidly progressive multiple thromboses leading to multiorgan failure occur in less than 1% of patients and named as catastrophic antiphospholipid syndrome (CAPS). We, hereby, describe an 8 year-old-girl with erythematous skin lesions progressing into purpura fulminans. The patient developed CAPS with the findings including proteinuria, microangiopathic hemolytic anemia, thrombocytopenia, arterial and venous thromboses demonstrated on skin biopsies. She was admitted to intensive care unit and received empirical antibiotics, anticoagulants, antiaggregants, steroids and intravenous immunoglobulins. The diagnosis of APS was confirmed by positive lupus anticoagulants, elevated anti beta-2 glycoprotein IgG and antiphospholipid IgG titers. Moreover, other than MTHFR-A1298C, MTHFR-C677T, factor V H1299R, beta fibrinogen-455 G >A heterozygosity indicating low risk for thrombophilia, no infectious, rheumatological or malignant etiologies were identified. Family history revealed Raynaud's phenomenon in a sister, interstitial lung disease, proteinuria and hematuria in paternal grandmother in addition to lupus anticoagulant positivity in father and 2 elder sisters. Her treatment included debridement of necrotic skin tissue, grefting and local mesenchymal stem cell application to upper thigh and lower leg region following oral azathioprine administration.

The Nijmegen Breakage syndrome (NBS) is characterized by chromosomal instability, combined immunodeficiency, and distinctive physical features. We present two siblings with NBS presenting with strikingly different manifestations. The proband is a 6-year-old female with short stature, microcephaly, hepatosplenomegaly, rectovaginal fistula, anal atresia, an ectopic kidney, recurrent fevers and otitis media. A 7-year-old brother has developmental delay, failure to thrive, and microcephaly without recurring infections. Both patients have hypogammaglobulinemia, B cell lymphopenia and reduced phytohaemagglutinin-induced lymphocyte proliferation. Both siblings are homozygous for the c.657_661delACAAA (p.Lys219Asnfs*16) mutation in the NBN (NBS1) gene.

BACKGROUND:Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by inborn errors of the phagocyte nicotinamide adenine dinucleotide phosphate oxidase complex. From the first year of life onward, most affected patients display multiple, severe, and recurrent infections caused by bacteria and fungi. Mycobacterial infections have also been reported in some patients.OBJECTIVE:Our objective was to assess the effect of mycobacterial disease in patients with CGD.METHODS:We analyzed retrospectively the clinical features of mycobacterial disease in 71 patients with CGD. Tuberculosis and BCG disease were diagnosed on the basis of microbiological, pathological, and/or clinical criteria.RESULTS:Thirty-one (44%) patients had tuberculosis, and 53 (75%) presented with adverse effects of BCG vaccination; 13 (18%) had both tuberculosis and BCG infections. None of these patients displayed clinical disease caused by environmental mycobacteria, Mycobacterium leprae, or Mycobacterium ulcerans. Most patients (76%) also had other pyogenic and fungal infections, but 24% presented solely with mycobacterial disease. Most patients presented a single localized episode of mycobacterial disease (37%), but recurrence (18%), disseminated disease (27%), and even death (18%) were also observed. One common feature in these patients was an early age at presentation for BCG disease. Mycobacterial disease was the first clinical manifestation of CGD in 60% of these patients.CONCLUSION:Mycobacterial disease is relatively common in patients with CGD living in countries in which tuberculosis is endemic, BCG vaccine is mandatory, or both. Adverse reactions to BCG and severe forms of tuberculosis should lead to a suspicion of CGD. BCG vaccine is contraindicated in patients with CGD.

The severity and duration of immunosuppression caused by corticosteroids (CSs) usage have not been extensively studied. We aimed to investigate the effects of CSs on the various compartments of immune system in relation to timing of initiation and persistence of therapy. Pediatric patients with idiopathic nephrotic syndrome (NS) treated with 2 mg/kg/day prednisolone and healthy control (HC) were enrolled. Blood samples were drawn for immunologic analyses at baseline and at the first and second weeks and first, second, and third months of CS therapy in addition to first and second weeks and first, second, and third months of discontinuation. Fourteen patients (M/F, 7/7) between 1 and 8 years old were evaluated. Untreated NS exhibited high absolute lymphocyte count (ALC)(p = 0.010), absolute CD3+ T cells (p = 0.020) and absolute CD8+ T cells (p = 0.006) compared to HC. Suppression in ALC was observed and nadir value was noted at first month of therapy compared to baseline (p = 0.002). The CD4+ (p = 0.036) and CD8+ T cell (p = 0.013) counts decreased significantly at the first week of treatment compared to baseline. While baseline B cell counts was indifferent from HC, gradually increased in 2 weeks of CS initiation and decreased during the treatment with a statistical significance compared to HC (p = 0.010). However, after cessation of CS, B cell counts continued to decline and found to be significantly different than baseline at first week (p = 0.008) and at third month (p = 0.040).

Purine nucleoside phosphorylase (PNP) deficiency is characterized by T – B + NK + combined immune deficiency, presenting with neurological deterioration and recurrent infections. PNP is an essential enzyme taking a part in the purine salvage pathway, converting inosine to hypoxanthine, and guanosine to guanine reversibly. We described two patients with PNP deficiency caused by a novel point mutation in exon 5: c.593 C>T, predicting the p.P198L amino acid substitution. Both patients presented with developmental delay and severe lymphopenia without any serious recurrent infections. Children with developmental delay and hypouricemia should be screened for PNP deficiency, especially in the presence of lymphopenia.

Systemic lupus erythematosus (SLE) is a challenge for pediatricians due to the heterogeneity of its clinical manifestations and the rarity of the disorder in this age group. Neuropsychiatric SLE (NPSLE) was defined especially in adult patients and the clinical course of this manifestation is still not clearly defined in the pediatric age group. We, here report a five-year old girl presenting with extensive maculopapular skin lesions, oral ulcers and neuropsychiatric symptoms. She had elevated titers of anti-nuclear antibody (ANA), Anti-ds-DNA, anti-histone antibodies and complement levels. Serum coxsackie and cytomegalovirus (CMV) IgM tests were positive, as well. Magnetic resonance imaging (MRI) of the brain demonstrated extended cerebral and cerebellar atrophy. Pediatricians should be attentive to the possibility of neurolupus for patients with neurological problems despite a young age at presentation. Appropriate therapy is a challenging task.

Atopic dermatitis (AD) is a chronic inflammatory skin disease, often complicated by recurrent microbial super infections. Numerous studies demonstrated increased frequency of allergen-specific Th2 cells producing increased IL-4, IL-5 and IL-13 in the peripheral blood of AD patients, however little is known about the role of natural killer (NK) cells. In this study, NK1, NK2 and NK regulatory cytokine profiles, the expression of activatory receptors as well as the cytotoxic activity of NK cells in AD patients was investigated. The study group consists of children without treatment (n=8, mean age=8 ± 3.7 years), under treatment (n=14, mean age=7 ± 4.3 years), and healthy subjects (n=14, mean age=11 ± 4.2 years). Patients were multisensitized and had high serum total IgE levels. NK cells were studied by their cytotoxic capacity, expression of CD16 & CD56, activatory receptors and intracellular IL-4, IL-10 & IFN-g levels by flow cytometry. The percentages of CD3-CD16+CD56+ NK cells were significantly diminished in patients under treatment. Compared to healthy subjects, CD16brightCD56dimNK cell subset was significantly increased in the group without treatment however decreased in those under treatment. In all patients, IL-10 secreting regulatory and IL-4 secreting NK2 cells were increased, however, expression of activatory receptors, NKG2D and NKp46, cytotoxic capacity of NK cells and NK1 cell subset were significantly decreased compared to healthy subjects. Our findings suggested impaired NK cell functions in AD patients and imply a decrease of IFN-g production by NK1 cells, which may partially be responsible for the tendency to develop viral infections.