CHONDROITIN-4-SULFATE (PROTEOGLYCAN), A RECEPTOR FOR PLASMODIUM-FALCIPARUM-INFECTED ERYTHROCYTE ADHERENCE ON BRAIN MICROVASCULAR ENDOTHELIAL-CELLS

Adherence of Plasmodium falciparum parasitized erythrocytes to the mic rovascular endothelium is mediated by different receptors expressed by endothelial cells. The study of the adherence of P. falciparum-infect ed erythrocytes to Saimiri monkey brain microvascular endothelial cell s revealed the presence of apr additional receptor, which was identifi ed and further characterized. This receptor was also found on the surf ace of primary human lung endothelial cells (HLEC). We developed two m Abs to this receptor which very efficiently blocked the adherence of p arasite strains to Saimiri brain endothelial cells (SBEC). The ability of these mAb to bind to SBEC was partially blocked by chondroitin-4-s ulphate (CSA). Competitive inhibition assays on adherence of parasitiz ed red blood cells (PRBC) showed that CSA, but not hyaluronic acid, ch ondroitin-6-sulphate, dermatan sulphate, keratane sulphate, heparan su lphate or chondroitin-4S-disaccharide, was able to almost completely i nhibit PRBC adherence. The same effect was obtained with chondroitinas e ABC and AC, but not B, hyaluronidase or heparinase. These results st rongly suggest that a member of the chondroitin-glycosaminoglycan fami ly, CSA, represents an additional receptor used by P. falciparum PRBC to cytoadhere to microvascular endothelial cells.