Clinical features, severity, and immunological changes during venom immunotherapy in children and adults.

Background: Hymenoptera venom allergy (HVA) is among the most common causes of severe allergic reactions worldwide. Objective: To investigate clinical features and factors that affect the severity of HVA and to determine the alterations in immunologic biomarkers after venom immunotherapy (VIT). Methods: Seventy-six adults and 36 children were prospectively investigated. We analyzed specific immunoglobulin E (sIgE) and sIgG4 levels of venom extracts and components (rApi m1, rApi m10, rVes v1, rVes v5, rPol d5) before and after the first year of VIT. Results: Although cardiovascular symptoms were more common in adults (p < 0.001), the skin was the most affected organ in children (p = 0.009). Serum basal tryptase (sBT) levels were higher in the adults than the children (p < 0.001). The absence of urticaria (odds ratio [OR] 4.208 [95% confidence interval {CI}, 1.395-12.688]; p = 0.011) and sBT ≥ 5.2 ng/mL (OR 11.941 [95% CI, 5.220-39.733]; p < 0.001) were found as the risk factors for grade IV reactions. During VIT, changes in sIgE levels were variable. In the Apis VIT group, we observed remarkable increases in sIgG4 levels in Apis extract and rApi m1 but not in Api m10. Vespula extract, rVes v1, and rVes v5 sIgG4 levels were significantly increased in Vespula VIT group, we also detected significant increases in the Polistes extract and rPol d5 sIgG4 levels, which were not observed in the Apis VIT group. In the patients who received both Apis and Vespula VIT, increases in sIgG4 levels were observed for both venoms. Conclusion: Adults and children can have different clinical patterns. After 1 year, VIT induced a strong IgG4 response. Although Apis immunotherapy (IT) induced Apis sIgG4, excluding Api m10, Vespula IT induced both Vespula and Polistes sIgG4.