Platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes is a common adhesive phonotype and is associated with severe malaria

Sequestration of malaria-infected erythrocytes in the peripheral circulatio n has been associated with the virulence of Plasmodium falciparum, Defining the adhesive phenotypes of infected erythrocytes may therefore help us to understand how severe disease is caused and how to prevent or treat it. We have previously shown that malaria-infected erythrocytes may form apparent autoagglutinates of infected erythrocytes. Here we show that such autoagglu tination of a laboratory line of P. falciparum is mediated by platelets and that the formation of clumps of infected erythrocytes and platelets requir es expression of the platelet surface glycoprotein CD36, Platelet-dependent clumping is a distinct adhesive phenotype, expressed by some but not all C D36-binding parasite lines, and is common in field isolates of P, falciparu m. Finally, we have established that platelet-mediated clumping is strongly associated with severe malaria. Precise definition of the molecular basis of this intriguing adhesive phenotype may help to elucidate the complex pat hophysiology of malaria.