title: Identification and characterization of a human thymus-leukemia antigen (43-kDa/513TL) bearing a structural relationship to HLA.
abstract: A human thymus-leukemia-like antigen has been identified that is antigenically distinct from T6/HTA-1. This was accomplished with a rabbit antiserum (513) which was prepared against lymphoblasts that were E rosette negative (E-), human thymus antigen positive (HuTA+), cALLA-, DR-, SmIg- from a patient who presented with a mediastinal mass and a WBC count of 130 X 10(9) cells/1. Following absorption with B cell and "null" cell lines, 513 exhibited prominent reactivity with a membrane antigen that was present on normal thymocytes and lymphoblasts from 11 of 13 patients with T cell ALL and 1 of 16 patients with common ALL, but was not detected on normal peripheral blood lymphocytes, normal bone marrow cells and leukemic lymphoblasts with an undifferentiated phenotype. SDS-PAGE analysis of this antigen indicated that it was composed of two subunits, 43-kDa and 12-kDa. Sequential absorption experiments revealed that: (1) the 12-kDa subunit was antigenically similar to beta 2 microglobulin; (2) the intact molecule did not exhibit HLA-A, B or C "framework" determinants; (3) the molecule was antigenically distinct from a human thymus-leukemia antigen HTA-1 (recognized by monoclonal antibodies NA1/34 and OKT6); and (4) the molecule was antigenically distinct from adenosine deaminase. It is concluded that 513 reacts with a membrane protein (designated 513TL) which exhibits properties characteristic of a histocompatibility-like antigen whose expression is restricted to thymocytes and some leukemias (TL antigen). Its antigenic distinction from another recently characterized human TL antigen, HTA-1, suggests polymorphism among this family of alloantigens.
mesh_terms: D000243:Adenosine Deaminase / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology* / Q000302:isolation & purification; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D007945:Leukemia, Lymphoid / Q000276:immunology*; D008562:Membrane Glycoproteins; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D006680:HLA Antigens; D008562:Membrane Glycoproteins; C028388:thymus-leukemia antigens; D000243:Adenosine Deaminase