B cell subpopulations in the mouse: Analysis with monoclonal antibodies NIM‐R2 and NIM‐R3

Abstract

Two rat monoclonal antibodies, NIM‐R2 and NIM‐R3, have been produced using the rat myeloma line 210RCY3‐Agl.2.3 and spleen cells from Lou rats immunized with mouse spleen cell plasma membrane or cells. The antibodies identify nonoverlapping populations of surface Ig‐positive cells in the spleen and a large (95%) proportion of bone marrow cells. Both recognize differentiation antigens in that the surface representation of the markers changes during the development of the cell. The NIM‐R3 specificity does not appear until three weeks of age in both the spleen and bone marrow and may be on a more mature set of cells. In contrast, the NIM‐R2 antibody, which stains the pre‐B cell line 70Z/3 and binds to neonatal cells, may recognize pre‐B cells in the bone marrow. There was no Clear‐cut correlation between the presence or absence of surface IgM, surface IgD or complement receptors on B cells positive or negative for either NIM‐R2 or NIM‐R3. Most interesting was the finding of identical total surface Ig densities on cells which stained weakly or strongly with NIM‐R2, since these two B cell sub‐populations are shown to be enriched for memory and virgin B cells, respectively. To bias the production of monoclonal antibodies to distinct populations of cells, the immunogen for the NIM‐R3 fusion was depleted of cells strongly reactive with NIM‐R2. This method is of general applicability in the production of monoclonal antibodies to complementary populations of cells.