Analysis of two new leukemia-associated antigens detected on human T- cell acute lymphoblastic leukemia using monoclonal antibodies

Two monoclonal antibodies (anti-3–3 and anti-3–40) were produced, which identify two new leukemia-associated antigens. Both antibodies reacted with most cell lines derived from patients with T lymphoblastic leukemia (T-ALL), but were not detected on suspensions of normal hematopoietic cells (including thymocytes) by cytotoxicity, absorption, or indirect immunofluorescence assays. Analysis of fresh leukemic cells indicated that anti-3–3 only reacted with T-ALL cells, while anti-3–40 also reacted with some non-T, non-B ALL cells and a few acute myelocytic leukemia (AML) cells. The 3–40 antigen was also found histopathologically in frozen sections of several normal tissues, including the epithelial cells and a few lymphoid cells of the thymus, and some malignant tissues. The 3–3 antigen was not found in any tissue studied. A “double absorption” assay provided additional serologic evidence that the two antibodies identify different antigenic determinants. Biochemical analysis indicated that the molecules immunoprecipitated by anti-3–3 and anti-3–40 have molecular weights of 35,000–40,000 daltons. This study demonstrated that the 3–3 and 3–40 antigens are markers for human T-ALL and can be used along with the normal T-lymphocyte antigen, 3A1, to discriminate T-ALL from cutaneous T-cell lymphoma (CTCL), adult T-cell leukemia (ATL), and T-cell chronic lymphocytic leukemia (T-CLL).