A novel monoclonal antibody induces the differentiation of monocyte leukemic cells

A cell surface antigen (possibly a receptor) on human myeloid cell lines, that may play a crucial role in the differentiation of promonocytic cells, was detected by a murine monoclonal antibody (MAb 710F). When the myeloid cell lines, HL-60, THP-1 and U937, were cultured with the MAb 710F following pretreatment with phorbol 12-myristate 13-acetate (PMA), they displayed both cellular spreading and a strong adherence to the culture dish substratum. On transforming from their original round shape, the induced cells displayed the well-developed microvilli, spindles, or raffles that are characteristic of macrophages or dendrocytes. Similar morphological changes were not induced by treatment with either PMA or MAb 710F alone. By contrast, the lymphoid cell lines did not respond to these reagents. These results suggested that a signal for cellular adhesion and cytoskeletal reconstitution was triggered by the binding of MAb 710F to an antigen on the PMA-primed cells. Thus, the antigen 710F, which is preferentially expressed on peripheral blood monocytes, may represent a cell surface receptor closely associated with differentiation. The antigen/receptor 710F was shown to be a N-glycosylated protein with Mr. of 35-70k. This MAb may prove useful as a tool for both studies on the differentiation of myeloid lineage cells as well as on monocyte/macrophage adhesion function.