Monoclonal antibody against myeloid leukemia cell line (KG-1).

A murine monoclonal antibody (WI-5) was produced against a myeloid leukemia cell line (KG-1). The antibody was immunoglobulin G3K. It reacted only against KG-1 cells and failed to react against 33 other cell lines representing fibroblasts, solid tumors, and cells of myeloid and lymphatic origin. It also showed no reaction against normal red blood cells, granulocytes, platelets, monocytes, and T- and B-lymphocytes. Similarly, there was no reaction against lymphocytes transformed by mitogens. Peripheral blood and bone marrow samples from acute granulocytic and acute lymphocytic leukemia, chronic granulocytic leukemia, chronic granulocytic leukemia in blastic crisis, and chronic lymphocytic leukemia failed to react with WI-5. It was suggested that WI-5 detected a unique antigen on KG-1 cells.

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.

Monoclonal antibody (WI-2) reactive against human transformed and leukemic cells.

A monoclonal antibody (WI-2) was produced against HL-60 cells. This antibody was IgM Kappa and reacted with human cell lines derived from fibroblasts and from hemopoetic, lymphoid, and neoplastic tissues. It also reacted with lymphocytes transformed by mitogens. WI-2 lacked reactivity against normal human RBC's, mature granulocytes, and T and B lymphocytes. The target antigen for WI-2 had a molecular weight of 43,000 daltons. Specimens from patients with leukemia were tested with WI-2. The number of immature cells was compared with the number of WI-2 reactive cells in the peripheral blood and bone marrow and subjected to linear regression analysis. There was a highly significant (p less than 0.001) correlation between the two parameters. The antibody may be useful in monitoring the progress of the patients and in detecting early relapse in leukemia.