Factors Influencing Invasion of Erythrocytes by Plasmodium falciparum Parasites: The Effects of an N-Acetyl Glucosamine Neoglycoprotein and an Anti-Glycophorin a Antibody

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  • * Division of Communicable Disease and Immunology, Walter Reed Army Institute of Research, Washington, DC 20307-5100
  • ** Laboratory of Parasitic Disease
  • Department of Transfusion Medicine, National Institutes of Health, Bethesda, Maryland 20205

When schizont-infected erythrocytes were incubated with N-acetyl glucosamine coupled to bovine serum albumin (GluNAc-BSA), the number of new ring forms which appeared several hours later was reduced and the number of abnormal and unruptured schizont-infected erythrocytes was increased compared with controls, indicating that GluNAc-BSA prevents invasion by a toxic effect on schizonts rather than by receptor blockade. Invasion of erythrocytes by Plasmodium falciparum was inhibited by a monoclonal antibody against glycophorin A, but inhibition also occurred with P. knowlesi, a parasite that is known to invade independently of glycophorin A. Inhibition of invasion with anti-glycophorin A is unlikely to be related to receptor blockade and is probably related to decreased deformability of the erythrocyte membrane caused by the binding of this antibody. Previous studies suggesting that GluNAc-BSA and anti-glycophorin A antibodies inhibit invasion by receptor blockade should be reevaluated. Erythrocytes deficient in glycophorin C and band 4.1 were also resistant to invasion by both P. falciparum and P. knowlesi.