Differentiation antigen on murine B lymphocytes defined by monoclonal antibodies

Spleen cells from an AKR/J X DBA/2J F1 mouse immunized with NZB/BIN spleen cells were fused with SP2/0-Ag14. Two hybrid cell lines, B220-1 and B220-2, were established that secreted antibody to the B-lineage specific B220 antigen. B220-1 and B220-2 are present on 45-55% of splenic and bone marrow lymphocytes and absent from thymus. By flow cytometry, all immunoglobulin-bearing cells were stained by these monoclonal antibodies. Although these monoclonals do not stain thymocytes, they do react weakly with Lyt-2+ peripheral T cells. Dual parameter analysis of B lymphocytes using RA3-3A1 or 14.8 show that these monoclonals recognized the same population. Prior incubation with RA3-3A1 or 14.8 was unable to completely block the binding of B220-1 or B220-2, implying that the epitopes recognized are different from the previously described monoclonal antibodies. Immunoprecipitation of the splenic lymphocyte reveals a molecule which migrates on SDS-PAGE as a single band with MW of 220,000 daltons. Expression of the distinct antigens recognized by B220-1 and B220-2 varied among mouse strains, indicating previously unappreciated polymorphism of the B220 molecule. These monoclonals are useful for cytotoxic elimination of B cells and for three-color flow cytometry.