Memorial Sloan Kettering Cancer Center

Robert W Knowles

Bo Dupont

Yasuo Morishima

Kazuyuki Naito

Two monoclonal antibodies (3-3 and 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 of indirect immunofluorescence assays. Analysis of fresh leukemic cells indicated that mAb 3-3 only reacted with T-ALL cells, while mAb 3-40 reacted with some non-T non-B ALL cells and a few acute myelocytic leukemia (AML) cells, as well as T-ALL 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, while the 3-3 antigen was not found in any tissue studied. A 'double absorption' assay provided additional serological evidence the the two antibodies identify different antigenic determinants. Biochemical analysis indicated that the molecules immunoprecipitated by mAb 3-3 and mAb 3-40 have molecular weights of 35-40,000 daltons. It is 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).

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New York, NY, United States of America

Robert W Knowles