title: CD3 and CD2 ligation alters CD49d epitope expression.
abstract: The combination of anti-CD2 plus anti-CD3 monoclonal antibodies (mAbs) synergistically prolongs allograft survival and induces antigen-specific tolerance. Since altered expression of cell surface molecules might be important for tolerance induction, the effect of anti-CD2 and anti-CD3 mAbs on the expression of adhesion molecules was analyzed on splenic T cells with an in vitro model. The anti-CD2 mAb, 12-15, alone had no effect on the expression of integrin alpha 4-chain epitopes recognized by two anti-CD49d (VLA-4 alpha) mAbs, R1-2 and PS/2. The anti-CD3 mAb, 2C11, caused R1-2 epitope expression to decrease, while PS/2 epitope expression remained unchanged. The combination of anti-CD2 and anti-CD3 mAbs further decreased R1-2 epitope expression while preserving PS/2 epitope expression. The expression of integrin beta 1 and beta 7 chains, each of which form heterodimers with alpha 4 chains, also remained unchanged. Expression of other integrin, selectin, or immunoglobulin superfamily molecules (CD11a, CD18, CD44, CD45, CD48, CD54 and CD62L) were all significantly increased by anti-CD2 or anti-CD3 mAbs. Decreased R1-2 epitope expression was anti-CD3 dependent and specifically augmented by anti-CD2 mAb. CD2-regulated decreases in R1-2 epitope expression correlated with increased cAMP and could be prevented by addition of high doses of IL-2 but was not affected by the addition of other cytokines. R1-2 alpha 4 epitope expression could be specifically restored by the divalent cation Mn2+, which also increased functional binding to the VCAM-1 ligand. Significantly, the R1-2 but not the PS/2 mAb prolonged graft survival in a cardiac allograft model. These results show that anti-CD2 and anti-CD3 mAbs selectively decrease integrin alpha 4 chain epitope expression on T cells through conformational regulation. Decreased expression of a CD49d epitope is unique in comparison to the up-modulation of other T-cell adhesion receptors. These changes correlate with functional effects and provide an additional mechanistic explanation for the synergistic effect of anti-CD2 plus anti-CD3 in producing tolerance.
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor 48109-0331, USA.
authors.forename: J
authors.initials: J
authors.lastname: Lin
authors.forename: L
authors.initials: L
authors.lastname: Qin
authors.forename: K D
authors.initials: KD
authors.lastname: Chavin
authors.forename: Y
authors.initials: Y
authors.lastname: Ding
authors.forename: J D
authors.initials: JD
authors.lastname: Punch
authors.forename: Q
authors.initials: Q
authors.lastname: Yang
authors.forename: L C
authors.initials: LC
authors.lastname: Burkly
authors.forename: J S
authors.initials: JS
authors.lastname: Bromberg
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism*; D018801:CD2 Antigens / Q000276:immunology / Q000378:metabolism*; D017252:CD3 Complex / Q000276:immunology / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D000939:Epitopes / Q000276:immunology / Q000378:metabolism; D005260:Female; D006084:Graft Rejection / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology; D039441:Integrin alpha4; D016023:Integrins / Q000096:biosynthesis; D008024:Ligands; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D011485:Protein Binding / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018801:CD2 Antigens; D017252:CD3 Complex; D015815:Cell Adhesion Molecules; D000939:Epitopes; D016023:Integrins; D008024:Ligands; D039441:Integrin alpha4