Phenotype analysis of lymphocyte subsets in normal human bone marrow.

T-lymphocyte subsets in marrow aspirates taken from normal donors were analyzed with the use of monoclonal antibodies and flow cytometry. Peripheral blood specimens from the same donors were analyzed concurrently and served as controls. Eighty-six percent of CD8-positive cells from marrow expressed the pan-T-cell markers CD2 and CD3, compared with 91% and 81%, respectively, of CD8-positive cells from peripheral blood. Virtually all CD8-positive marrow lymphocytes, however, were negative for CD11b as opposed to peripheral blood, where 18% exhibited positivity for this marker. Further, a higher percentage of marrow CD8-positive T-lymphocytes expressed HLA-DR (15.4%) than did those from peripheral blood (4%). Marrow CD4-positive subsets did not differ substantially from those of peripheral blood. These results support the concept of a selective homing of CD8-positive T-cells to the marrow and indicate that CD8-positive T-cells in the marrow are effector T-cells.