Effect of fucoidin on IRBC rolling on immobilized soluble P-selectin. IRBC suspended in increasing concentrations of fucoidin, a sulfated homopolymer of fucose, in HBSS were infused over immobilized P-selectin. Dextran and chondroitin sulfate A, two other carbohydrates with no known interaction with P-selectin, were used as controls. Values represent the mean number of rolling cells ± SEM for 5 clinical P falciparum isolates studied.