Identification of a leukocyte alloantigen with a high-frequency expression in leukemia patients

In this report we describe the production and characterization of a monoclonal antibody to the human promyelocytic leukemia cell line HL-60. The antibody, NC-2, is of the IgG1 subclass and precipitates a 50-Kd protein from¹²⁵I-labeled HL-60 cells. The antigen is insensitive to treatment with trypsin, papain, or neuraminidase. NC-2 did not react with a number of established human cell lines, including Daudi, Molt-4, K562, U937, KG-1, CEM, Raji, and Gash-P. Neutrophils and monocyte-like cells derived from HL-60 cells that were induced to differentiate continued to express the antigen. NC-2 reacted with all peripheral-blood cells except erythrocytes from eight (5%) of 150 normal individuals tested. Bone marrow samples from patients with myelogenous leukemias were more frequently reactive with NC-2 than were those from normal individuals (12/33 v 1/10). Family studies indicated that the antigen was inherited in an autosomal-dominant manner. These findings suggest that the expression of the above alloantigen is associated with an increased incidence of leukemia.