Differentiation Antigens of HL-60 Promyelocytes during Induced Maturation1

The human promyelocytic leukemic cell line HL-60 can be induced to mature monocytes and macrophages in vitro by lymphocyte-conditioned medium. We are reporting sequential changes in surface antigenic expressions, which are sensitive markers of the characteristic events in the process of cell differ entiation. The promyelocyte membrane antigen, detected by a monoclonal antibody produced using HL-60 cells as an immunogen, was shown to be associated with immature myeloid cells and was used to determine HL-60 cell development. The expres sion of this membrane antigen, determined to have a molecular weight of 85,000 was lost early in the differentiation period. In the following stage, in which the promyelocytes developed into monocytic cells, a steady increase of cells bearing the OKM1 normal monocyte antigen was observed. When macrophages became predominant in the final culture period, the expression of the OKM1 antigen decreased. The usefulness of these differ entiation antigens in studying cellular development is discussed.