title: Differential down-regulation of CD28 by B7-1 and B7-2 engagement.
abstract: Physiologically relevant full activation of T cells requires signal transduction through the T cell receptor and additional costimulatory cell surface molecules. Best understood of these costimulatory interactions are those between CD28 and its ligands B7-1 (CD80) and B7-2 (CD86). While B7-1 and B7-2 bind the same receptors (CD28 and CTLA-4), they share only 25% sequence homology, are expressed at different times during immune responses, and in some systems have been shown to differentially affect T cell cytokine expression. Although CD28 is an activation antigen, its expression is down-regulated after engagement by B7-1. Here we show that B7-2 engagement is considerably less effective at down-regulating CD28, which indicates a differential effect of these two CD28 ligands on activated T cells.
authors.affiliation: Department of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Eck
authors.forename: D
authors.initials: D
authors.lastname: Chang
authors.forename: A D
authors.initials: AD
authors.lastname: Wells
authors.forename: L A
authors.initials: LA
authors.lastname: Turka
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000494:pharmacology*; D018122:B7-1 Antigen / Q000494:pharmacology*; D051940:B7-2 Antigen; D018106:CD28 Antigens / Q000502:physiology*; D016466:CHO Cells / Q000378:metabolism; D006224:Cricetinae; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D018106:CD28 Antigens; C497965:Cd86 protein, mouse; D008562:Membrane Glycoproteins