MULTIPLE PLATELET SURFACE-RECEPTORS MEDIATE PLATELET-ADHESION TO SURFACES COATED WITH PLASMA-PROTEINS

The interactions between platelets and plasma proteins previously show n to adhere to biomaterials were evaluated, using monoclonal antibodie s (mAbs) against specific platelet surface glycoprotein (GP) receptors . Purified Cr-51-labeled human platelets in plasma-free medium were in cubated with each of the following antibodies: mAb 10E5 [anti-GP IIb/I IIa; fibrinogen, von Willebrand factor (vWF), and fibronectin receptor ]; mAb 6D1 (anti-GP Ib-IX; vWF receptor); mAb IV.3 (anti-Fc gamma RII; IgG receptor); polyclonal antiserum A108 or mAb BIIG4 (anti-GP Ic-IIa ; fibronectin receptor). Antibody-treated platelets were added to micr otiter wells coated with fibronectin, fibrinogen, vWF, IgG, vitronecti n, albumin, or platelet-poor plasma (PPP). Cr-51-labeled platelet adhe sion to matrix proteins was expressed as a percentage of that measured on PPP-coated surface. Platelets adhered to fibrinogen, fibronectin, vWF, or IgG immobilized on polystyrene. Limited binding to either vitr onectin or albumin was detected. Binding to fibrinogen and IgG was blo cked by mAb 10E5. Binding to IgG was also blocked by mAb IV.3. Binding to fibronectin, reduced in the presence of mAb 10E5, mAb BIIG4, or th e polyclonal antiserum A108 alone, was further reduced by combined 10E 5 and BIIG4 or 10E5 and A108. Neither mAb 10E5 nor 6D1 alone blocked a dhesion to vWF; however, the combination of 10E5 and 6D1 significantly reduced platelet adhesion to this matrix, Finally, platelet adhesion to the plasma-coated surface was reduced by mAbs 10E5 and BIIG4. These results indicate that multiple adhesion receptors can mediate platele t adhesion to matrix proteins immobilized on surfaces. (C) 1994 Academ ic Press, Inc.