Correlation of immunological and clinical findings in wasp venom-allergic patients before and after sting challenge

The immunological effects of an in-hospital sting challenge in wasp venom-a llergic patients during venom immunotherapy (VIT) are largely unknown. The aim of the study was to analyze the influence of such a sting challenge on the proliferation and cytokine production of peripheral blood mononuclear c ells (PBMC) and to investigate whether the venom-specific proliferation und cytokine secretion allows to predict the result of the sting challenge. Al l 15 patients included in this study had a history of severe systemic aller gic reactions to wasp stings as well as positive skin tests and wasp-venom- specific IgE in the sera (RAST class greater than or equal to 2). Additiona lly, they showed no reduction in specific IgE antibodies or skin test react ivity after VIT. The sting challenge was carried out 3 to 4 years after ini tiation of VIT to examine the efficacy of VIT in this specially selected gr oup of patients. PBMC were isolated from heparinized blood before and four weeks after the sting challenge and the venom-specific proliferation and th e venom-induced secretion of cytokines after primary stimulation with wasp venom and restimulation with anti-CD3 and anti-CD28 mAb were measured. Only one patient showed a severe systemic reaction with hypotension, five patie nts presented an exaggerated local reaction and the other patients showed n o allergic signs after sting challenge. The in vitro data 4 weeks after sti ng challenge revealed a slight increase of the venom-specific proliferation and IL-4 production as well as a somewhat stronger increase in IL-5 produc tion, whereas the IFN-gamma secretion after the sting challenge decreased s lightly (all data not statistically significant). It was not possible to pr edict with certainty the outcome of the sting challenge from the data descr ibed above.