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Platelet adhesion to collagen in individuals lacking glycoprotein IV

1994; Elsevier BV; Volume: 83; Issue: 10 Linguagem: Inglês

10.1182/blood.v83.10.2866.2866

1528-0020

Laurie P. McKeown, M Vail, Sybil B. Williams, W. Kramer, K Hansmann, H R Gralnick,

Complement system in diseases

Abstract The Naka isoantigen is expressed on glycoprotein (GP) IV (CD36), a platelet membrane GP that has been identified as having a role in platelet interactions with collagen and thrombospondin and in binding Plasmodium falciparum-infected erythrocytes to endothelial cells and melanoma cells. We have studied normal platelets and Naka- platelets from two Japanese donors that have 1% of GPIV by concentration- dependent antibody binding and flow cytometry. We studied the adherence of normal and Naka- platelets to types I, III, and IV collagen in static and to type I collagen in flowing systems at high shear force. We have also studied aggregation of normal and Naka- platelets to type I collagen. Naka- platelets showed normal or increased aggregation to type I collagen and normal adhesion to types I, III, and IV collagen in the presence of Mg++ or EDTA. Platelet aggregation and adhesion were inhibited by the anti-alpha 2 beta 1 antibody 176D7 to the same extent in Naka- as in normal platelets. We also studied endogenous thrombospondin surface expression and found that thrombin-stimulated Naka- platelets expressed the same amount of thrombospondin as did normal platelets. From our studies with Naka- platelets, we cannot identify a definitive role for GPIV in platelet aggregation, in adhesion to types I, III, and IV collagen, or in endogenous thrombospondin binding to platelets.