Production and analysis of HH 10 monoclonal antibodies reactive to immature hematopoietic cells and their use for monitoring acute leukemia cells.

A clone of murine monoclonal antibody HH 10 (IgM) was raised by fusing NS-1 myeloma cells and spleen cells of a mouse hyperimmunized with acute promyelocytic leukemia cells. Serological analysis by means of immune adherence assays showed that HH 10 reacts with immature hematopoietic cells including thymocytes and myeloid precursor cells (defined as colony-forming units in culture assays). The antibodies were not reactive to either peripheral blood cells or bone marrow cells obtained from normal individuals. Lymphoid blasts induced with phytohemagglutinin, pokeweed mitogen, or concanavalin A were also non-reactive, and all non-hematopoietic cultured cells examined were also negative. The antibodies were, however, reactive to leukemia cells in 67 cases out of 91 cases (74%) of acute leukemia. In patients with acute lymphoblastic leukemia, 43 out of 52 cases (83%) were positive and, in particular, all of 12 T-cell-type acute leukemias were reactive to HH 10. Comparison of percent HH 10 positive cells in the bone marrow of patients with acute leukemia with the results of cytological studies showed a good correlation. Analysis of sequentially collected bone marrow cells of acute leukemia patients using HH 10 revealed its usefulness for monitoring leukemia cells.