In vitroinhibition ofPlasmodium falciparummerozoite invasion by human plasma fibronectin

Human fibronectin isolated from citrated blood was tested for its ability to bind to Plasmodium falciparum by an indirect immunofluorescent assay using rabbit antiserum to human fibronectin. A positive reaction was observed on merozoites inside schizont-infected erythrocytes. The binding was not observed on non-parasitized red blood cells. The effect of human fibronectin on P. falciparum growth was further studied using an in vitro inhibition assay; 50% inhibition of parasite multiplication was obtained with approximately 100 micrograms/ml of human fibronectin. Slight inhibition was observed below 10 micrograms/ml. The significance of this finding is discussed.