Immunological and clinical factors associated with adverse systemic reactions during the build-up phase of honeybee venom immunotherapy.

BACKGROUND: Adverse systemic reactions (SRs) are more common in honeybee venom immunotherapy (VIT) than in wasp VIT. Factors that might be associated with SRs during the honeybee VIT are poorly understood. OBJECTIVE: Our aim was to evaluate risk factors for SRs during the build-up phase of honeybee venom immunotherapy. METHODS: We included 93 patients who underwent ultra-rush honeybee VIT. The adverse SRs and their severity was compared to various immunological (sIgE, tIgE, basophil CD63 response, baseline tryptase, and skin tests), patient-specific (age, sex, cardiovascular conditions and medications, and other allergic diseases), and sting-specific factors (anaphylaxis severity, time interval to onset of symptoms, and absence of cutaneous symptoms). RESULTS: Twenty-three patients (24.7%) experienced mild SRs and 13 patients (14%) severe SRs. In five patients with severe SRs, the build-up was stopped. High basophil allergen sensitivity, evaluated as dose-response curve metrics of EC15, EC50, CD-sens, AUC, or the response to submaximal 0.01 µg/mL of venom concentration, was the most significant risk factor and only independent predictor of severe SRs and/or build-up stop. Time interval of <5 min after sting to onset of symptoms and lower specific IgEs to rApi m1 was also associated with severe SRs. There was no difference in other immunological, patient-specific, or sting-specific factors, including the baseline tryptase. None of the studied factors was associated with mild SRs. CONCLUSION AND CLINICAL RELEVANCE: High basophil allergen CD63 sensitivity phenotype was a major indicator of severe adverse SRs during the build-up phase of honeybee VIT. Possibly role was also showed for short latency to filed sting reaction and low sIgE to rApi m1. Before honeybee VIT, measurement of basophil allergen sensitivity should be used to identify patients with a high risk for severe side-effects.

Immunoglobulin G-dependent changes in basophil allergen threshold sensitivity during birch pollen immunotherapy.

BACKGROUND: The effects of pollen immunotherapy on effector cells of allergic inflammation, such as mast cells and basophils, are poorly understood. OBJECTIVE: For this reason, we conducted an open study on basophil allergen threshold sensitivity during birch pollen immunotherapy. METHODS: Basophil sensitivity was measured by CD63 flow cytometry in 14 patients with moderate-severe intermittent birch pollen rhinitis using four log allergen concentrations. In nine patients, we analysed the basophil sensitivity before and during treatment with subcutaneous birch immunotherapy (perennial scheme with allergoid). We also included eight birch-allergic donor subjects for IgG inhibition experiments and eight control subjects. RESULTS: There was a decrease in basophil allergen threshold sensitivity after 2, 3, and 5 months of immunotherapy. This decrease was correlated with an improvement in patients' symptoms measured on a visual analogue scale. The serum obtained after immunotherapy induced a significant decrease in allergen threshold sensitivity in donor birch-allergic basophils. This inhibition was not observed after IgG depletion from the serum. CONCLUSIONS: In this study, we showed that birch immunotherapy-induced IgG antibodies are associated with a reduction in basophil allergen threshold sensitivity. Further studies are needed to show whether the changes in basophil sensitivity are of clinical relevance in pollen immunotherapy.