MHC (RT1) restriction of the antibody repertoire to infection with the nematode Nippostrongylus brasiliensis in the rat.

It might be expected that infections with transmissible agents will elicit an immune response to all of their exoantigens and that immune response (Ir) gene control of responses to individual epitopes on a given parasite component would be obscured by reaction to the molecule as a whole. Humans infected with parasitic nematodes, however, mount antibody responses which are selective for certain parasite components. This was modelled in inbred rats infected with the parasitic nematode Nippostrongylus brasiliensis and their responses to secreted antigens analysed by immunoprecipitation and SDS-PAGE. No strain responded to all the potential antigens and only those of identical major histocompatibility complex (MHC) had similar recognition profiles. This MHC-restricted response applied to whole molecules synthesized by the parasite, rather than merely to epitopes thereon and is, therefore, contrary to expectation. Moreover, the response patterns of F1 hybrid animals were not merely summations of parental responses. This suggests defective antigen presentation of particular parasite components by certain MHC class II molecules and/or cross-tolerance with background gene products.