Species-specific allergens from the salivary glands of Triatominae (Heteroptera:Reduviidae).

We investigated allergenic cross-reactivity among species of the blood-feeding insects of the subfamily Triatominae. By skin testing, patients allergic to either Triatoma protracta or T. rubida gave positive responses only to the respective salivary antigen. RAST-inhibition experiments demonstrated that binding of IgE antibodies to T. protracta antigen was not inhibited by salivary extracts from T. rubida, T. cavernicola, T. rubrofasciata, or Rhodnius prolixus. The same level of species specificity was found for IgE antibodies to T. rubida. By direct RAST, no T. rubida positive serum bound T. protracta antigen, and 29 of 30 T. protracta positive sera failed to bind T. rubida. One serum from a T. protracta-allergic patient contained IgE antibodies to both T. protracta and T. rubida. RAST-inhibition experiments demonstrated that these antibodies did not cross-react and that this person had separate species-specific antibodies to T. protracta and T. rubida antigens. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of salivary extracts demonstrated that the lower molecular weight bands that contain the antigens responsible for human allergic reactions differed in number and size in all species tested. These studies demonstrate species specificity for the allergic response to Triatoma and stress the importance of accurate insect identification and the need for species-specific antigens for diagnosis and immunotherapy.