Influence of total and specific IgE, serum tryptase, and age on severity of allergic reactions to Hymenoptera stings

P>Background: The aim of this study was to analyze the influence of total serum IgE and other potential risk factors on severity of systemic allergic Hymenoptera sting reactions. Methods: In a retrospective analysis of one thousand and two patients referred for insect allergy over 5 years, 865 reported systemic allergic sting reactions, most often by honey bees and wasps. In 758, total IgE, venom-specific IgE, and baseline tryptase levels were available and analyzed together with atopy state, age, and sex in relation to severity of sting reactions according to H. L. Mueller. Results: In a binary logistic regression model considering, besides IgE, also other risk factors for severity, an influence of total and specific IgE on severity of systemic allergic sting reactions could not be shown, while high severity of systemic allergic sting reactions was significantly more often reported in patients with a baseline tryptase of >= 11.4 mu g/l (P < 0.0001) and higher age (P = 0.026). In a bivariate analysis, however, in patients with grade IV reactions total IgE (P = 0.003) and honey bee venom-specific IgE (P = 0.001) were significantly lower than in lower severity grades. Bee venom-specific mean IgE rank was significantly higher in bee than in Vespula venom allergic patients (P = 0.0001). Conclusions: Connection of high severity sting reactions with lower IgE is mainly because of older age, which is associated with lower total IgE, and moreover with cardiovascular disease and elevated baseline serum tryptase, which are both risk factors for severe reactions.