Immunologic mechanisms in mosquito allergy: correlation of skin reactions with specific IgE and IgG antibodies and lymphocyte proliferation response to mosquito antigens.

BACKGROUND: Allergic reactions to mosquito bites are a common problem. Although IgE-mediated hypersensitivity has been reported, other immunologic mechanisms may be involved.

OBJECTIVES: To study the relationship between skin bite reactions and immunologic parameters.

METHODS: Forty-one subjects were experimentally exposed to mosquito (Aedes vexans) bites. Immediate and delayed skin reactions were traced at 20 minutes and 24 hours, respectively, after the bites. Sera were analyzed for mosquito salivary gland-specific IgE (mosquito-IgE) and IgG (mosquito-IgG) by ELISA. Lymphocyte proliferation assays with mosquito extract were also performed.

RESULTS: One of 41 subjects had only a delayed skin reaction to the bite, 23 had both immediate and delayed reactions, 6 had only immediate reactions, and 11 had no reaction. The mean mosquito-IgE and -IgG concentrations were higher in the subjects with immediate reactions than in those without immediate reactions (P < .007). The mean lymphocyte proliferation stimulation index was higher in the subjects with delayed reactions than in those without delayed reactions (P < .015). Further, both mosquito-IgE and -IgG levels correlated with skin immediate and delayed reactions (P < .04), while lymphocyte proliferation indices only correlated with skin delayed reactions (P < .006). Inverse correlations were found between the size of skin reactions and the number of years lived in Canada (P < .04), but not with age.

CONCLUSION: These results indicate that IgE-, lymphocyte- and, probably, local IgG immune-complex-mediated hypersensitivities are involved in mosquito allergy. Naturally acquired desensitization to mosquito bites occurs during long-term exposure.