The Journal of Immunology, Vol 156, Issue 1 284-288, Copyright © 1996 by American Association of Immunologists

ARTICLES

A common epitope on platelet integrin alpha IIb beta 3 (glycoprotein IIbIIIa; CD41b/CD61) and alpha M beta 2 (Mac-1; CDIIb/CD18) detected by a monoclonal antibody

MO De Nichilo, DR Shafren, WM Carter, MC Berndt, GF Burns and AW Boyd
Cancer Research Unit, Faculty of Medicine, University of Newcastle, New South Wales, Australia.

Evidence is presented that the mAb 25E11, directed against the platelet integrin alpha IIb beta 3 (glycoprotein IIbIIIa;CD41b/CD61) also binds the distinct myeloid cell integrin alpha M beta 2 (Mac-1;CDIIb/CD18). The Ab is shown to identify only the alpha IIb beta 3 integrin complex and not the individual subunits in crossed Ab immunoelectrophoresis of platelet lysate. From cultured human macrophages, sequential immunoprecipitation of labeled glycoproteins indicated that 25E11 also bound the Mac-1 (CD11b/CD18) complex. This was confirmed using COS-7 and WOP cells doubly transfected with alpha M (CD11b) and beta 2 (CD18) or with alpha L (CD11a) and beta 2 when it was found that the Ab bound only the alpha M beta 2 transfectants. Studies with these cells and the RC2A myeloid cell line stimulated with tetradecanoyl phorbol acetate or FMLP indicated that the 25E11 epitope on Mac-1 did not depend on cell activation for its expression. The rationale for this cross-reactivity is not known, but since the 25E11 Ab inhibits the function of both platelets and myeloid cells, it is likely that this shared epitope is important to integrin function. Given the expression of this epitope on IIbIIIa and Mac-1, the dominant integrins of platelets and granulocyte/macrophage cells, but not on other integrins, a role of this epitope in the early events of inflammation is suggested.

This article has been cited by other articles:

				J. Plescia, M. S. Conte, G. VanMeter, G. Ambrosini, and D. C. Altieri Molecular Identification of the Cross-reacting Epitope on alpha Mbeta 2 Integrin I Domain Recognized by Anti-alpha IIbbeta 3 Monoclonal Antibody 7E3 and Its Involvement in Leukocyte Adherence J. Biol. Chem., August 7, 1998; 273(32): 20372 - 20377. [Abstract] [Full Text] [PDF]

				R. G. Sitrin, P. M. Pan, S. Srikanth, and R. F. Todd III Fibrinogen Activates NF-{kappa}B Transcription Factors in Mononuclear Phagocytes J. Immunol., August 1, 1998; 161(3): 1462 - 1470. [Abstract] [Full Text] [PDF]

				D. I. Simon, H. Xu, S. Ortlepp, C. Rogers, and N. K. Rao 7E3 Monoclonal Antibody Directed Against the Platelet Glycoprotein IIb/IIIa Cross-reacts With the Leukocyte Integrin Mac-1 and Blocks Adhesion to Fibrinogen and ICAM-1 Arterioscler. Thromb. Vasc. Biol., March 1, 1997; 17(3): 528 - 535. [Abstract] [Full Text]

				T. J. Kunicki, D. S. Annis, Y.-J. Deng, J. C. Loftus, and S. J. Shattil A Molecular Basis for Affinity Modulation of Fab Ligand Binding to Integrin alpha IIbbeta 3 J. Biol. Chem., August 23, 1996; 271(34): 20315 - 20321. [Abstract] [Full Text] [PDF]