[Erythrocytes infected by Plasmodium falciparum activate human platelets].

Blood platelets are involved in Plasmodium falciparum malaria pathology as shown by thrombocytopenia and increased plasma level of two alpha granule proteins: beta thromboglobulin (beta TG) and platelet factor 4 (PF4). In this study we demonstrate that Plasmodium falciparum parasitized erythrocytes activate directly the secretion of beta TG and PF4 by human platelets. This secretion is related to parasitemia and occurs immediately after contact. Treatment of parasited erythrocytes by trypsin and diffusion chamber experiments suggest that platelet activation is triggered by parasitic substances shed on erythrocyte membrane and released in the culture medium.