Myeloid progenitor surface antigen identified by monoclonal antibody

A mouse monoclonal antibody, WM-15, has been developed which reacts with a human myeloid lineage-restricted cell surface antigen. WM-15, an IgG1 antibody, reacts with a mean of 3.8% of normal bone marrow mononuclear cells, identifying predominantly promyelocytes and myeloblasts, and in fluorescence-activated cell sorting experiments produces enrichment of bone marrow granulocyte-macrophage progenitor cells. Normal mature monocytes and granulocytes are weakly labelled by WM-15, but other haemopoietic cells including erythroblasts and all lymphoid cells are unreactive. The myeloid specificity of this antibody is highlighted by its reactivity with myeloid leukaemia cell lines and 65% of cases of acute myeloid leukaemia, while lymphoid cell lines and leukaemias are WM-15 negative. WM-15 appears to be a useful reagent for further investigation of normal and abnormal myelopoiesis.