A new mouse cell-surface antigen (Ly-m20) controlled by a gene linked to Mls locus and defined by monoclonal antibodies

Five monoclonal antibodies were established by the fusion of mouse myeloma cells (NS.1) with spleen cells from A and (A x C3H/An)F₁ mice hyperimmunized with 70Z/3 tumor cells. These antibodies recognized a new antigenic specificity provisionally called Ly-m20.2. In direct cytotoxicity assays, 60 percent of cells in spleen, 40 percent in lymph node, 50 percent in bone marrow and less than 5 percent in thymus were found to react with three of the five antibodies, whereas the two others yielded somewhat lower cytotoxicity indices. The Ly-m20.2 antigen was also expressed on cells derived from liver and kidney but not on cells derived from brain. As judged from cytotoxicity assays with separated T and B cells, Ly-m20.2 antigen is carried preferentially on B lymphocytes. Direct plaque-forming cells (PFC) were completely eliminated by Ly-m20.2-specific antibody and complement. Linkage tests by analysis in 20 (CBA/J x C3H/An) x C3H/An backcross mice and by segregation analysis of BXH and SWXL recombinant inbred strains indicate close association of the loci controlling Ly-m20.2 and Mls antigens on chromosome 1.Abbreviations used in this paper MLR mixed lymphocyte reaction - MHC major histocompatibility complex - Mls minor lymphocyte-stimulating antigen - Ia I-region associated - PFC plaque-forming cell - SRBC sheep red blood cell - Con A concanavalin A - LPS lipopolysaccharide - GVH graft-versus-host - HVG host-versus-graft - CML cell-mediated lympholysis - LD lymph ocyte-defined - SD serologically definedThe prefix m (monoclonal) is used following a suggestion by Klein and co-workers (1979).