Adhesive functions of platelets lacking glycoprotein IV (CD36).
Glycoprotein IV (GPIV; CD36 or GPIIIb) is a cell surface glycoprotein that has been proposed as mediating a number of physiologically important processes such as the adhesion of platelets to thrombospondin (TSP) and collagen, the cytoadherence of Plasmodium falciparum-infected erythrocytes, and the TSP-dependent interaction of monocytes with platelets and macrophages. Because platelets of the Naka-negative phenotype have recently been shown to lack detectable GPIV, their availability offered the opportunity to test directly these hypotheses regarding its adhesive functions. It has been found that Naka-negative platelets and monocytes do not support cytoadherence of P falciparum-infected erythrocytes. Naka-negative platelets are deficient in the initial stages of their adhesion to fibrillar collagen and this defect is most marked under Mg(2+)-free conditions. Finally, the ability of Naka-negative platelets to bind TSP before or after activation is unimpaired as compared with normal controls. These results do not support a role for GPIV as the TSP receptor.
Tandon
N N
NN
American Red Cross, Cell Biology Laboratory, Rockville, MD 20855.
Ockenhouse
C F
CF
Greco
N J
NJ
Jamieson
G A
GA
D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology*; D018955:CD36 Antigens; D003094:Collagen / Q000378:metabolism; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D016778:Malaria, Falciparum / Q000503:physiopathology*; D010963:Plasmodium falciparum; D010973:Platelet Adhesiveness; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D019699:Thrombospondins
D015703:Antigens, CD; D018955:CD36 Antigens; D010980:Platelet Membrane Glycoproteins; D019699:Thrombospondins; D003094:Collagen