Characterization of human IgE and mouse IgG1 responses to allergens in three mosquito species by immunoblotting and ELISA

Background: IgE-mediated allergic reactions caused by mosquito bites are a common problem all over the world. This study was undertaken to determine IgE levels in subjects, to elucidate human IgE and mouse IgG1 binding patterns and to investigate the cross-reactivity of salivary gland antigens with three mosquitoes. Methods: Mosquito larvae of Aedes togoi, Culex tritaeniorhynchus and Culex pipiens pallens were collected and maintained in the laboratory. Salivary gland extracts (SGE) and whole-body extracts (WBE) were prepared from female mosquitoes of each species. Mosquito-specific IgE levels in 17 subjects were measured by ELISA. Polypeptide patterns were analyzed by SDS-PAGE. Immunoblotting was performed with sensitized human and immune mouse sera, and elucidated human IgE and mouse IgG1 binding patterns to SGE. For the determination of cross-reactivity to the three types of mosquitoes, ELISA inhibition tests were performed using sera from mice sensitized by biting of A. togoi. Results: The 9 sera out of 12 with positive skin reactions to SGE of A. togoi by skin prick test showed significantly higher anti-mosquito SGE IgE levels than in those without skin reactions. Protein band patterns of the SGE and WBE of the three species were different from one another. Specific human IgE reacted to the protein in SGE of 30.5, 33, 37 and 57.5 kD from A. togoi, of 38, 43 an 68 kD from C. tritaeniorhynchus, and of 23, 33, 34, 43, 44, 60, 74 and 93 kD from C. pipiens pallens. There were specific mouse IgG1 reactions to the bands of 30.5, 33, 37 and 57.5 kD in the SGE of A. togoi. The ELISA inhibition studies disclosed almost no cross-reactivities between A. togoi, C. tritaeniorhynchus and C. pipiens pallens. Conclusions: Immunoblot analysis disclosed that allergenic proteins in the SGE of mosquitoes and their patterns were remarkably similar between human and mouse sera to the SGE of A. togoi. Species-shared allergens may not exist among the three mosquito species prevalent in Korea.