title: Ia-bearing T lymphocytes in man. Their identification and role in the generation of allogeneic helper activity.
abstract: The presence of Ia-like antigens was demonstrated on a small population (2-6%) of highly purified human circulating T lymphocytes by immunofluorescence with a rabbit anti-Ia serum raised against the isolated bimolecular Ia structure. The Ia+ T lymphocytes have no surface or intracellular immunoglobulins. The expansion of this Ia+ T-cell population was encountered in certain patients. Ia antigens were also found on T blasts grown in long-term cultures with conditioned medium generated by phytohemagglutinin-stimulated lymphocytes. In addition, leukemia blasts which stained for Ia antigens and formed E rosettes were identified in the peripheral blood of two leukemic patients. This evidence further supports the existence of Ia-bearing T cells in man. The Ia+ T-lymphocyte population was shown to contain cells responsible for the generation of allogeneic helper activity. Elimination of Ia+ lymphocytes from a purified T-cell population by the anti-Ia antiserum and complement abolished its ability to help an allogeneic B-cell preparation to generate plaque-forming cells against sheep erythrocytes in vitro in the presence of the antigen.
mesh_terms: D000954:Antigens, Surface / Q000235:genetics; D002478:Cells, Cultured; D008040:Genetic Linkage; D006680:HLA Antigens / Q000235:genetics; D006801:Humans; D007519:Isoantigens / Q000235:genetics; D007938:Leukemia / Q000276:immunology; D008211:Lymphocyte Cooperation; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D006680:HLA Antigens; D007519:Isoantigens