The "adjuvant effect" of the polymorphic B-G antigens of the chicken major histocompatibility complex analyzed using purified molecules incorporated in liposomes.

The polymorphic B-G region of the chicken major histocompatibility complex has previously been shown to mediate an "adjuvant effect" on the humoral response to other erythrocyte alloantigens. We demonstrate here that B-G molecules purified with monoclonal antibodies exert this adjuvant effect on the production of alloantibodies to chicken class I (B-F) molecules, when the two are in the same liposome. The adjuvant effect may in part be mediated by antibodies, since the antibody response to B-G molecules occurs much faster than the response to B-F molecules, and conditions in which antibodies to B-G are present increase the speed of the response to B-F molecules. We also found that the presence of B-G molecules in separate liposomes results in a lack of response to B-F molecules. In the light of this and other data, we consider the possible roles for the polymorphic B-G molecules, particularly for the generation of B cell diversity, in the immune systems of birds and other animals.