title: Interaction of CTLA-4 (CD152) with CD80 or CD86 inhibits human T-cell activation.
abstract: Occupancy of CTLA-4 (cytotoxic T-lymphocyte antigen-4 or CD152) negatively regulates the activation of mouse T lymphocytes, as indicated by the fate of CTLA-4-deficient mice, by the impact of anti-CTLA-4 monoclonal antibodies (mAbs) on mouse T-cell activation in vitro and by the impact of CTLA-4 blockade on the course of experimental tumoral, autoimmune, alloimmune or infectious disease in this animal. The function of human CTLA-4, however, remains less clear. The expression and function of human CTLA-4 were further explored. CTLA-4 was expressed under mitogenic conditions only, its expression being, at least partially, dependent on the secretion of interleukin-2. Memory T cells expressed CTLA-4 with faster kinetics than naive T cells. The functional role of human CTLA-4 was assessed utilizing a panel of four anti-CTLA-4 mAbs that blocked the interaction between CTLA-4 and its ligands. These mAbs, in immobilized form, profoundly inhibited the activation of T cells by immobilized anti-CD3 mAb in the absence of anti-CD28 mAb, but co-stimulated T-cell activation in the presence of anti-CD28 mAb. Finally, and importantly, blockade of the interaction of CTLA-4 with its ligands using soluble anti-CTLA-4 mAbs, in intact form or as Fab fragments, enhanced T-cell activation in several polyclonal or alloantigen-specific CD80- or CD80/CD86-dependent assays, as measured by cytokine production, cellular proliferation or cytotoxic responses. It is concluded that interaction of CTLA-4 with its functional ligands, CD80 or CD86, can down-regulate human T-cell responses, probably by intracellular signalling events and independent of CD28 occupancy.
authors.affiliation: Laboratory for Experimental Hematology, University of Leuven, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Vandenborre
authors.forename: S W
authors.initials: SW
authors.lastname: Van Gool
authors.forename: A
authors.initials: A
authors.lastname: Kasran
authors.forename: J L
authors.initials: JL
authors.lastname: Ceuppens
authors.forename: M A
authors.initials: MA
authors.lastname: Boogaerts
authors.forename: P
authors.initials: P
authors.lastname: Vandenberghe
mesh_terms: D000069594:Abatacept; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology*; D000943:Antigens, Differentiation / Q000276:immunology* / Q000378:metabolism; D018122:B7-1 Antigen / Q000276:immunology*; D051940:B7-2 Antigen; D018106:CD28 Antigens / Q000276:immunology; D060908:CTLA-4 Antigen; D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D018796:Immunoconjugates; D008213:Lymphocyte Activation / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D018106:CD28 Antigens; C497964:CD86 protein, human; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; D000069594:Abatacept