Mast cell activation syndrome (MCAS) is a challenging specialized condition that allergists-immunologists treat in the outpatient setting. Despite the wide prevalence of the disease, clinicians may feel overwhelmed to provide consistent compassionate care for these patients for a multitude of reasons. Patients uniformly describe feeling unheard during a clinical encounter and thereby often end up seeing multiple physicians and specialists which further complicates their medical care. As such, it is important to characterize patients with MCAS accurately, which includes the assessment of coexistent mimicking or confounding conditions to achieve best medical care outcomes.
Hereditary alpha-tryptasemia (HαT) is a common autosomal dominant genetic trait that results from increased copy numbers of the TPSAB1 gene encoding α-tryptase. Studies have shown that increased relative α-tryptase expression can modify mast-cell-mediated reactions and contribute to increased severity of anaphylaxis. HαT is an independent risk modifier for reaction severity in patients with Hymenoptera venom allergy and systemic mastocytosis. Additionally, there is emerging evidence that HαT and α-tryptase expression more generally are also associated with increased risk of severe reactions to other allergens. Tryptase genotyping may be a promising biomarker for risk stratification of IgE-mediated allergic reaction severity in the future.
Allergy to venoms of stinging insects (bees, yellow jackets, hornets, wasps, and stinging ants) causes large local reactions or systemic reactions, including anaphylaxis. Diagnostic evaluation includes skin testing and/or serum venom-specific IgE and basal serum tryptase (to identify underlying mast cell disorders). Patients with sting anaphylaxis should be prescribed epinephrine and venom immunotherapy which prevents allergic reactions in up to 98% of patients. Most patients may safely discontinue venom immunotherapy after 5 years, although high-risk patients need to continue indefinitely. Further research is needed to improve the predictive value of diagnostic testing and the safety and efficacy of treatment.
Anaphylaxis can be caused by several different mechanisms. Novel therapies on the horizon target these numerous pathways, including tyrosine kinase inhibitors, recombinant allergen-specific blocking antibodies, and monoclonals targeting KIT or inhibitory receptors. This article discusses potential new therapies for both the prevention and treatment of anaphylaxis that are currently in clinical development.
Anaphylaxis is a potentially life-threatening allergic reaction that is increasing worldwide. While it is often straightforward to diagnose, at times the diagnosis remains uncertain, especially if there is no clear trigger, symptoms overlap with other conditions, or patients mainly report subjective symptoms without confirmatory physical findings. Unfortunately, there is no gold-standard test for diagnosing anaphylaxis, so clinicians must rely on clinical criteria to assess its likelihood. The first widely accepted clinical criteria were published in 2006 by the National Institute of Allergy and Infectious Diseases and the Food Allergy and Anaphylaxis Network, and in 2020, the World Allergy Organization proposed updates to these criteria. The new 2024 Anaphylaxis Clinical Support Tool addresses discrepanices between previous criteria.
Anaphylaxis is a life-threatening allergic condition that affects all ages, and research suggests that prevalence is increasing worldwide. The changing epidemiology of anaphylaxis is attributable to factors such as improved diagnosis, new drug therapies, climate change, and changes in national and international guidelines. Risk factors for severe and fatal anaphylaxis include older age, lung disease, beta-blockers, angiotensin-converting enzyme inhibitors, cardiovascular disease, and mast cell disorders. Furthermore, epidemiology of anaphylaxis is variable depending on the trigger. Understanding anaphylaxis epidemiology is important to support identification of patients at higher risk and candidates for therapies that can reduce future anaphylaxis risk.
Immediate hypersensitivity reactions (IHRs) to iodinated contrast media generally occur due to non-immunoglobulin E (IgE)-mediated release of histamine and other inflammatory mediators from mast cells and basophils. IgE-mediated reactions have also been described. Although premedication was previously recommended routinely for prior reactors, based on the substantially lower rate of IHR with low osmolar contrast media, premedication has become controversial as to whether the potential for benefit exceeds the potential for harm. Switching contrast agents, skin testing to contrast agents, drug provocation testing, and rapid drug desensitization are additional risk-reduction strategies that can be considered in properly selected patients.
Food-induced anaphylaxis incidence rates in 0 to 19 year-olds and 0 to 4 year-olds are reported as 0.2 and 7.0 per 100 person years respectively, with increased hospitalizations reported in the United States. Avoidance has been our traditional approach to prevent food-induced anaphylaxis and it involves reading nutrition labels, understanding forms of allergen exposure, food allergy policies outside the home, and communicating effectively about personal risk. Active approaches have also emerged including oral immunotherapy and omalizumab, which are both Food and Drug Administaration-approved. Many other options are currently in development, for example, epicutaneous immunotherapy, sublingual immunotherapy, and a variety of biologic drugs.
Health equity is achieved when all individuals can reach their full health potential. In food-induced anaphylaxis, this goal remains unmet. Disparities in prevalence, diagnosis, and care are influenced by race, income, and environmental determinants. This article reviews emerging evidence on inequities in food allergy, emphasizing the need to understand who is most affected and why, and outlining strategies to promote equitable prevention and treatment.
Anaphylaxis is a systemic clinical syndrome that rapidly evolves after an exposure to an inciting agent activates effector cells such as mast cells and basophils. Anaphylaxis can be triggered by a wide variety of agents, including drugs. Over the past decade, our understanding of drug-induced anaphylaxis (DIA) has become dramatically more nuanced, with a growing appreciation of multiple endotypes resulting in the phenotype of anaphylaxis. This review will discuss epidemiology, clinical features, mechanisms, clinical evaluation, and management of DIA.
