Allergy to insect stings. I. Diagnosis of IgE-mediated Hymenoptera sensitivity by venom-induced histamine release

The failure to distinguish sensitive from normal individuals by skin testing with whole body extracts of Hymenoptera led us to study whether "allergic" reactions to these insects were based on an immunologic mechanism and to attempt the development of a useful diagnostic test for this condition. Pure venoms of honeybee, yellow jacket, yellow and white-faced hornets, and bumblebees were used as antigens for leukocyte histamine release. The leukocytes from 13 16 patients judged clinically to have had systemic reactions to a stinging insect released > 50 per cent of their histamine with 0.001 to 1.0 μg per milliliter of venom. Whether the few patients who had a negative response were truly allergic or sensitive to venoms not used for testing remains to be seen. None of the leukocytes of the 12 control patients, however, released histamine at 1,000-fold greater concentrations of venom. We confirmed previous studies which showed that skin testing with Hymenoptera whole body extracts failed to separate these two groups. Passive sensitization of normal leukocytes for venom-induced histamine release was accomplished with sera from several of the Hymenoptera-sensitive patients. Heating these sera to 56 ° C. or passing them through an IgE immunoabsorbent column markedly reduced their sensitizing ability. We conclude that venom-induced histamine release from the leukocytes of Hymenoptera-sensitive patients is mediated by antibodies of the IgE class and suggest that the great majority of reactions to Hymenoptera stings are truly allergic. The clear-cut diagnostic utility of pure venoms in vitro warrants further exploration of their diagnostic utility by in vivo skin testing.