title: Two mouse monoclonal antibodies detecting two different epitopes of an activated lymphocyte antigen on adult T-cell leukemia cells.
abstract: Mouse monoclonal antibodies were produced against MT-2 cell line derived from adult T-cell leukemia or human T-cell leukemia virus-rich fraction therefrom. Two IgG1 antibodies, Ta60a and Ta60b, were found to be reactive not only with cell lines derived from adult T-cell leukemia or cutaneous T-cell lymphomas, but also with activated peripheral blood lymphocytes, suggesting the similarity of Ta60 antigen group to Tac antigen which is present on interleukin 2 receptor. Thus, the relationship among these antigens was studied. Two Ta60 antibodies and Tac antibody immunoprecipitated the molecule with almost identical electrophoretic mobility, approximately a Mr 60,000 antigen from [3H]glucosamine-labeled activated peripheral blood lymphocytes or MT-2, MT-1, or ATN-1 cells from adult T-cell leukemia and a Mr 53,000 antigen from HUT-102 cells derived from cutaneous T-cell lymphomas. Further, Tac antibody was found to immunoprecipitate Ta60b molecule on 125I-labeled MT-2 cells by sequential immunoprecipitation, indicating that these two epitopes are on the same molecule. Antibody binding inhibition assays with either 3H-labeled Ta60a or Ta60b antibody demonstrated that Ta60a and Tac are the same epitope, but different from Ta60b. Thus, at least two epitopes were demonstrated to be present on interleukin 2 receptor molecule. However, Ta60b antibody showed almost no blocking effects on proliferation of an interleukin-2-dependent cell line, whereas Ta60a antibody did. Various hematopoietic tumor cells were typed with these two antibodies, but the results with Ta60b antibody were described, because they showed a similar specificity. Ta60b antibody reacted with all adult T-cell leukemia cases, but did not react with T-cell acute lymphoblastic leukemia, lymphoblastic lymphoma, or mature T-cell lymphoma. Interestingly, 3 of 12 acute myeloblastic leukemia and 2 of 5 chronic myelocytic leukemia in blastic crisis showed positive reactions. One-third of B-cell chronic lymphocytic leukemia and B-cell lymphoma as well as a few B-cell lines were also weakly reactive with this antibody. A part of the results with direct tests was confirmed by the absorption tests. The results obtained demonstrated the presence of Ta60b on a certain fraction of malignant hematopoietic cells of other than T-cell origin.
authors.forename: R
authors.initials: R
authors.lastname: Ueda
authors.forename: K
authors.initials: K
authors.lastname: Nishida
authors.forename: Y
authors.initials: Y
authors.lastname: Koide
authors.forename: I
authors.initials: I
authors.lastname: Tsuge
authors.forename: M
authors.initials: M
authors.lastname: Seto
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: I
authors.initials: I
authors.lastname: Miyoshi
authors.forename: K
authors.initials: K
authors.lastname: Ota
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000276:immunology*; D002460:Cell Line; D000939:Epitopes / Q000032:analysis*; D006413:Hematopoietic System / Q000276:immunology; D006801:Humans; D007938:Leukemia / Q000276:immunology*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D011971:Receptors, Immunologic / Q000032:analysis; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000939:Epitopes; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2