| Abstract: | Two monoclonal antibodies, prepared against a murine B lymphoma and characterized as binding to a cell surface antigen represented primarily on cells of the B lineage, were found to bind to human hemopoietic cells. These antibodies recognize similar populations of cells in mice and humans. Antibodies from clones 177.17 and 83.4 bound to 6% of human bone marrow nucleated cells. This included all cells with detectable cell surface Ig (sIg+) and those that lack sIg but have detectable cytoplasmic mu (sIg-, c mu+), considered to be the immediate precursors of B lymphocytes (pre-B cells). In addition, these antibodies bound to a subpopulation of T cells and a proportion of null lymphocytes in marrow, spleen, and peripheral blood. An unexpected finding was that established pre-B cell lines were not recognized by these antibodies and possible reasons for this are considered. By using antibody-coated polystyrene plates for cell depletion and recovery, highly enriched preparations of c mu+, sIg- cells have been obtained. These antibodies and enrichment procedures should prove valuable in establishing the minimal requirements for maturation of these putative precursors in vitro, for comparative studies of immunodeficiency/autoimmune diseases in man and experimental animal models, and for monitoring the outcome of therapeutic marrow transplantation. |
