title: A major costimulatory molecule on antigen-presenting cells, CTLA4 ligand A, is distinct from B7.
abstract: CTLA4 ligands are important costimulatory molecules because soluble CTLA4Ig blocks the induction of T cell responses and induces T cell tolerance. As CTLA4 immunoglobulin (CTLA4Ig) binds B7 when the latter is expressed on fibroblasts, it was widely assumed that CTLA4Ig blocks T cell costimulation by blocking the function of B7. Here we show that the major costimulatory ligand bound by CTLA4Ig (which we term CTLA4 ligand A) on antigen-presenting cells are not encoded by the B7 gene. CTLA4 ligand A also differs from B7 in cellular distribution and in the respective levels of expression. Both B7 and CTLA4 ligand A are critically involved in T cell costimulation.
authors.affiliation: Michael Heidelberger Division of Immunology, Department of Pathology, New York University Medical Center, New York 10016.
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000069594:Abatacept; D000818:Animals; D000911:Antibodies, Monoclonal; D000938:Antigen-Presenting Cells / Q000276:immunology*; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D001483:Base Sequence; D015704:CD4 Antigens / Q000276:immunology; D060908:CTLA-4 Antigen; D006224:Cricetinae; D017931:DNA Primers; D005434:Flow Cytometry; D015793:HLA-B7 Antigen / Q000096:biosynthesis* / Q000276:immunology*; D018796:Immunoconjugates; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D015704:CD4 Antigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D017931:DNA Primers; D015793:HLA-B7 Antigen; D018796:Immunoconjugates; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D000069594:Abatacept