title: Heterogeneity of bone marrow lymphocytes: radioautographic detection of pre-B cells bearing cytoplasmic mu chains, and of B and T lymphocytes, and characterization of null lymphoid cells.
abstract: A radioautographic immunolabeling technique has been developed to detect pre-B cells bearing cytoplasmic mu chains among populations of bone marrow lymphoid cells identified by conventional hematologic stains. 125I-Anti-mu antibody was applied either to fixed marrow smears, labeling total mu chains both in the cytoplasm (c mu) and at the cell surface (s mu), or to cell suspensions, labeling s mu alone. In stained radioautographs the incidence of c mu+ s mu- pre-B cells was derived both indirectly by subtracting values for s mu+ cells from those for total mu+ cells of various sizes in normal mice and directly by the total mu chain labeling in mice depleted of s mu+ cells by anti-IgM treatment in vivo. Binding specificity was demonstrated by the displacement of labeling by nonradioactive anti-mu antibody. The c mu+ s mu- cells showed a bimodal size distribution. They accounted for 40% of the large lymphoid cells and 30% of the small lymphocytes in the marrow. A further 50% of the small lymphocytes were B lymphocytes (s mu+) and 8% were T lymphocytes (Thy 1.2+). Thus, the technique demonstrates the presence of c mu+ s mu- pre-B cells among both proliferating large lymphoid cells and nondividing small lymphocytes, as classically defined in marrow smears. In addition, the results reveal a broad size distribution of mu- lymphoid cells, including a subset of small lymphocytes which lack c mu, s mu, and Thy 1.2 and thus cannot be assigned to either B or T lineage by these criteria. The findings suggest that in addition to B cells the marrow may produce other types of lymphoid cells, yet to be defined.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D001345:Autoradiography; D001402:B-Lymphocytes / Q000276:immunology; D001854:Bone Marrow Cells; D003593:Cytoplasm / Q000378:metabolism; D007148:Immunoglobulin mu-Chains / Q000378:metabolism; D008214:Lymphocytes / Q000145:classification* / Q000166:cytology; D008215:Lymphocytes, Null / Q000276:immunology; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology; D018800:Thy-1 Antigens
chemical_list: D000954:Antigens, Surface; D007148:Immunoglobulin mu-Chains; D018800:Thy-1 Antigens