Acquired immunity to Africanized honeybee (Apis mellifera) venom in Brazilian beekeepers

Seventy-eight Brazilian beekeepers who had been stung on average six times per month were studied. Sixty-eight beekeepers (87.1%) showed restricted local clinical reactions; nine individuals (11.5%) had extensive local reactions, and only one (1.2%) suffered anaphylactic shock. The humoral immunologic pattern of these individuals were studied by using immunoenzymatic methods to determine the serum titles of specific IgE and specific IgG4. Three groups of beekeepers presenting different humoral immunologic patterns were identified, in which the predominant pattern was the absence of specific IgE and high levels of specific IgG4 (38.4%). There was a positive correlation between the high levels of specific IgG4 and the number of bee stings. This correlation was not found in either specific or total IgE. The results of the present study suggest: i) the immunologic response to the number of exposures to Africanized honey-bee venom is not related to the number of exposures; and, ii) other nonhumoral and/or nonimmunologic factors may be involved in the reaction to the insect sting, which are responsible for both the clinical symptoms and protection.