Antigenic analysis of hematopoiesis. I. Expression of the My-1 granulocyte surface antigen on human marrow cells and leukemic cell lines

Five monoclonal antibodies that identify the My-1 human granulocyte surface antigen were not reactive with other peripheral blood cells. These antibodies effected complement-dependent cytolysis of a large fraction of normal human marrow leukocytes. This My-1-positive marrow cell population consisted of morphologically identifiable granulocytic precursor cells. Colony-forming cells of the granulocyte-monocyte lineage (CFC-GM) did not express My-1, suggesting that the My-1 antigen is expressed later in normal granulocytic maturation. However, these antibodies did react with myeloid leukemic cell lines. The significance and potential utility of these probes for the understanding of granulopoietic differentiation is discussed.