Monoclonal antibodies to hamster class II MHC molecules distinguish T and B cells.

Monoclonal antibodies were prepared against cell surface antigens present on Syrian hamster lymphocytes and a hamster B cell lymphoma line, GD-36. One of these antibodies, S11, precipitated glycoproteins of 29,000 and 39,000 m.w. These glycoproteins were shown to be identical to or a subset of la-like glycoproteins precipitated by hamster alloantisera; however, molecules identified by S11 differed from the predominant hamster la homologues detected with a cross-reactive monoclonal antibody to murine la.7. The immunofluorescence pattern of both anti-la reagents, S11 and anti-la.7, on hamster lymphoid cells is similar by fluorescence-activated cell sorter analysis. A subpopulation of spleen and lymph node cells stains brightly with these antibodies. By two-color fluorescence, this peripheral lymphocyte subpopulation, identified with monoclonal anti-hamster la, also bears surface immunoglobulin (IgM). These data strongly suggest that hamster resting peripheral B cells, and not T cells, express la antigens and can be identified and isolated differentially by using this marker.