Allergic reactions following first insect sting exposure.

Over a 10-year period, 750 patients were evaluated because of anaphylaxis following insect stings. Sixty-five patients were identified who had reactions after their first sting exposure. Their clinical features and symptoms of anaphylaxis were the same as the much larger group of patients who had allergic reactions following prior exposure to insect stings. When evaluated following the sting reaction, the majority of these patients had venom-specific IgE detected by skin test or in the serum by the RAST. Fifty-three re-stings occurred in 31 patients. In untreated or whole body extract-treated patients, there were 43 re-stings resulting in 13 reactions. There were no reactions following 10 re-stings in venom-treated patients. In a subgroup of 15 patients with undetectable venom-specific IgE, there were 16 re-stings in eight patients, leading to three systemic reactions. The occurrence of allergic reactions following first sting exposure adds further support to the thesis that some sting reactions are non-IgE-mediated.