Monoclonal antibody against a unique antigen on human acute promyelocytic leukemia cell line (HL-60).

An IgM kappa monoclonal antibody (WI-1) reacted against HL-60 cells in indirect immunofluorescence and microcytotoxicity tests. It failed to react against 19 other cell lines representing acute myelogenous leukemia, chronic myelogenous leukemia, lymphocytic leukemias, multiple myeloma, Burkitt's lymphoma, monocytoid cells and virus induced lymphoid cell lines. Normal peripheral blood nucleated cells and bone marrow cells derived from acute granulocytic leukemia, chronic granulocytic leukemia, acute lymphocytic leukemia, and chronic lymphocytic leukemia also failed to react with WI-1. Normal peripheral blood lymphocytes, transferred with mitogens, showed no reaction against the antibody. There was some decrease in the reactivity of the cells, against WI-1, following maturation with dimethyl sulfoxide. However, a large percentage of the cells remained positive after maturation. WI-1 reacted specifically against an antigen on the HL-60 cells which had a molecular weight of about 42,000 dalton. Peripheral blood cells from one patient with acute promyelocytic leukemia failed to react with the antibody. It is possible that acute promyelocytic leukemia is an antigenically heterogeneous disease. A large population of acute promyelocytic leukemia patients needs to be tested to see if the specific antigen on HL-60 cells, detected by WI-1, is demonstrable in other patients with acute promyelocytic leukemia.