title: Costimulation by extracellular matrix proteins determines the response to TCR ligation.
abstract: Although ligation of the T-cell antigen receptor (TCR) is central to the responsiveness and antigen specificity of T-cells, it is insufficient to elicit a response. To determine whether the need for costimulation reflects inadequate strength of signal transduction through the TCR or an absolute block of signaling in the absence of a coligand, we studied T-cell activation under serum-free conditions eliminating costimulation by various extracellular matrix proteins which otherwise have an omnipresent and frequently overlooked effect. Engagement of the TCR leads to induction of Fas, but not to measurable IL-2 secretion or apoptosis. Those activation parameters are induced by costimulation through integrin alphaVbeta3. Furthermore, T-cell survival or elimination is determined by the type of ligand binding to this coreceptor with vitronectin, fibronectin, and fibrinogen efficiently inducing apoptosis and IL-2 production while osteopontin and entactin mediate IL-2 secretion comparably without causing programmed cell death. Consistent with the cytokine properties of these ligands, differential costimulation depends on their presentation in soluble rather than immobilized form. The determination of elimination versus survival of activated T-cells by coligation of beta3-integrins may have bearing on the fundamental postthymic mechanisms that shape the T-cell repertoire.
authors.affiliation: Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Children's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: B
authors.initials: B
authors.lastname: Adler
authors.forename: S
authors.initials: S
authors.lastname: Ashkar
authors.forename: H
authors.initials: H
authors.lastname: Cantor
authors.forename: G F
authors.initials: GF
authors.lastname: Weber
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D002417:Cattle; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000494:pharmacology*; D006825:Hybridomas; D039661:Integrin beta3; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D009842:Oligopeptides / Q000494:pharmacology; D053495:Osteopontin; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000276:immunology*; D012795:Sialoglycoproteins / Q000737:chemistry / Q000494:pharmacology; D015398:Signal Transduction; D019096:Vitronectin / Q000494:pharmacology
chemical_list: D015703:Antigens, CD; D016326:Extracellular Matrix Proteins; D039661:Integrin beta3; D007376:Interleukin-2; D009842:Oligopeptides; D010980:Platelet Membrane Glycoproteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; D019096:Vitronectin; D053495:Osteopontin; C047981:arginyl-glycyl-aspartic acid