In a previous study we demonstrated that Plasmodium knowlesi-infected red cells have decreased deformability and suggested that this abnormality may be important in the pathophysiology of malaria. The present rheologic study was performed in monkeys infected by Plasmodium coatneyi in order to assess further the role of abnormal red cell deformability in the pathogenesis of disease. P. coatneyi is much more similar to P. falciparum than is P. knowlesi. Red cells infected by trophozoites and schizonts showed an increase of viscosity when suspended in Ringer's solution, caused increased resistance to flow through pores, 5 µ in diameter, in the polycarbonate sieve and were excluded from rouleaux formed in plasma. Ring forms produced less rheologic abnormality in the red cell than the more mature stages. These studies indicate that red cells infected by mature parasites of P. coatneyi have decreased deformability to the same extent as we observed in P. knowlesi. The possible relationship between the decreased deformability of infected red cells and cerebral malaria is discussed.
Present address: Laboratory of Parasitic Disease, NIAID, National Institutes of Health, Bethesda, Md. 20014. Career Development Awardee, NIAID, AI-24084.