The long range goal of this laboratory is to determine the function of histocompatibility-linked immune respose (Ir) genes in the regulation of the immune response and in the control of immunocompetent cell interactions. At present, the research effort is directed in two main areas: 1) the role of the I-region associated (Ia) antigens and Ir gene products in macrophage-T lymphocyte interaction, macrophage processing and presentation of antigen, and T-lymphocyte antigen recognition. 2) Genetic, serological, physicochemical, and functional studies of the antigens of the guinea pig major histocompability complex (the GPLA complex).