title: CD28:B7 interactions promote T cell adhesion.
abstract: CD28 activation by antibody-mediated ligation has been shown to provide an important co-stimulatory signal for T cell adhesion to purified protein ligands. However, the effect of CD28 ligation by one of its natural ligands, B7.1, on T cell adhesion to other cells has not been studied. Therefore, in the present manuscript, we characterized the adhesive interactions between human T cells and B7.1-transfected major histocompatibility complex class II+ and class II- melanoma cells. In our studies, human T cells and T cell clones adhered to B7.1-transfected melanoma cells, but not to untransfected parental cells. The adhesive reaction in this model was rapid, occurring within 15 min, and was inhibited by anti-B7.1 antibody and soluble CTLA-4 immunoglobulin. Antibody inhibition studies demonstrated that adhesion between T cells and B7.1-transfected melanoma cells was mediated by interactions between LFA-1:ICAM-1 and CD2:LFA-3. Inhibition by pharmacological agents demonstrated that the CD28-induced adhesion required specific intracellular signaling events. A protein kinase C inhibitor, staurosporin, significantly inhibited T cell binding to transfected melanoma cells, while cyclosporin A and wortmannin, an inhibitor of phosphatidylinositol-3-kinase, did not. These results suggest that the presence of B7 on various cell populations may activate lymphocytes to adhere better, thus promoting activation, cytolysis, and migration.
mesh_terms: D000069594:Abatacept; D000730:Androstadienes / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology / Q000502:physiology; D018122:B7-1 Antigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018106:CD28 Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D060908:CTLA-4 Antigen; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000502:physiology; D016572:Cyclosporine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D018796:Immunoconjugates; D007166:Immunosuppressive Agents / Q000494:pharmacology; D016023:Integrins / Q000502:physiology; D008545:Melanoma; D013601:T-Lymphocytes / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D018796:Immunoconjugates; D007166:Immunosuppressive Agents; D016023:Integrins; D000069594:Abatacept; D016572:Cyclosporine; D000077191:Wortmannin