title: Functional expression of B7/BB1 on activated T lymphocytes.
abstract: B7/BB1 is a membrane differentiation antigen expressed on activated B cells, macrophages, and dendritic cells that binds to a counter-receptor, CD28, expressed on T lymphocytes and thymocytes. Interaction between CD28 and B7 results in potent costimulation of T cell activation initiated via the CD3/T cell receptor complex. We now report that B7 is also expressed on activated human peripheral blood T cells, CD4 T cell clones, CD8 T cell clones, and natural killer cell clones. B7 appears relatively late after T cell activation, can be detected on both CD4 and CD8 T cell subsets, and is present on antigen-specific, major histocompatibility complex-restricted CD4 and CD8 T cell clones. Expression of B7 on activated T cells was confirmed by immunoprecipitation from 125I-labeled activated T cells and by detection of B7 transcripts. A B7+ CD4+ T cell clone was able to stimulate a primary allogeneic mixed lymphocyte response using small, resting peripheral blood T cells as responders. The alloantigen-induced proliferative response and cytokine production was partially inhibited by anti-B7 monoclonal antibody. Since activated T cells can coexpress both CD28 and its counter-receptor, B7, this suggests that activated T cells may be capable of autocrine costimulation via the CD28 activation pathway.
authors.affiliation: DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, California 94304.
authors.forename: M
authors.initials: M
authors.lastname: Azuma
authors.forename: H
authors.initials: H
authors.lastname: Yssel
authors.forename: J H
authors.initials: JH
authors.lastname: Phillips
authors.forename: H
authors.initials: H
authors.lastname: Spits
authors.forename: L L
authors.initials: LL
authors.lastname: Lanier
mesh_terms: D015703:Antigens, CD / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000502:physiology; D000954:Antigens, Surface / Q000032:analysis* / Q000235:genetics / Q000502:physiology*; D018122:B7-1 Antigen; D018106:CD28 Antigens; D017252:CD3 Complex / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis / Q000235:genetics; D006801:Humans; D007694:Killer Cells, Natural / Q000737:chemistry / Q000276:immunology / Q000648:ultrastructure; D008213:Lymphocyte Activation / Q000502:physiology*; D011233:Precipitin Tests; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology* / Q000648:ultrastructure; D014158:Transcription, Genetic
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018122:B7-1 Antigen; D018106:CD28 Antigens; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D004247:DNA