Quantitative differences in Ia antigen expression in the spleens of 15I5-B congenic and inbred chickens as defined by a new monoclonal antibody.

A monoclonal antibody (MAb), designated P2M11, that detects a monomorphic determinant of chicken class II antigens was produced from the fusion of P3X63 myeloma cells with spleen cells from BALB/c mice immunized with chicken splenic lymphocytes. Flow cytometric analyses of lymphocytes from the SC and FP strains of chickens showed 30 to 50% staining of bursa cells, 15 to 20% staining cells, and less than 5% staining of thymus cells. Addition of MAb P2M11 to splenic of T cell cultures stimulated with allogeneic cells or concanavalin A resulted in a significant inhibition of the T cell proliferation responses. Immunoprecipitation of 35S-methionine-labeled spleen cell extracts using MAb P2M11 identified molecules with apparent molecular weights of approximately 28,000, 30,000, and 32,000 by sodium dodecyl-polyacryl-amide gel electrophoresis. Taken together, these data indicate that the antigens detected by MAb P2M11 are similar in cell distribution and structure to chicken Ia antigens encoded by B-L genes. Using this MAb, a strain difference was demonstrated in the tissue distribution of Ia antigen positive lymphocytes in the spleens but not the thymuses of 15I5-B congenic and inbred strains of chickens. This difference may be due to the genes associated with B-complex genes.