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. 2000 May;68(5):2971-5.
doi: 10.1128/iai.68.5.2971-2975.2000.

Blood Group A Antigen Is a Coreceptor in Plasmodium Falciparum Rosetting

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Free PMC article

Blood Group A Antigen Is a Coreceptor in Plasmodium Falciparum Rosetting

A Barragan et al. Infect Immun. .
Free PMC article

Abstract

The malaria parasite Plasmodium falciparum utilizes molecules present on the surface of uninfected red blood cells (RBC) for rosette formation, and a dependency on ABO antigens has been previously shown. In this study, the antirosetting effect of immune sera was related to the blood group of the infected human host. Sera from malaria-immune blood group A (or B) individuals were less prone to disrupt rosettes from clinical isolates of blood group A (or B) patients than to disrupt rosettes from isolates of blood group O patients. All fresh clinical isolates and laboratory strains exhibited distinct ABO blood group preferences, indicating that utilization of blood group antigens is a general feature of P. falciparum rosetting. Soluble A antigen strongly inhibited rosette formation when the parasite was cultivated in A RBC, while inhibition by glycosaminoglycans decreased. Furthermore, a soluble A antigen conjugate bound to the cell surface of parasitized RBC. Selective enzymatic digestion of blood group A antigen from the uninfected RBC surfaces totally abolished the preference of the parasite to form rosettes with these RBC, but rosettes could still form. Altogether, present data suggest an important role for A and B antigens as coreceptors in P. falciparum rosetting.

Figures

FIG. 1
FIG. 1
Rosette disruption by immune sera in relation to ABO blood group. Nine samples of immune serum from healthy individuals, six of blood group A and three of blood group B, were tested for antirosetting activity on isolates from hosts of blood group A, B, or O. Antirosetting activity (percent inhibition of rosetting) is depicted in a five-level grey scale as indicated. Two serum samples from nonimmune Swedes (ni1 and ni2) were used as controls.
FIG. 2
FIG. 2
Binding of A antigen to surfaces of parasite-infected erythrocytes. (A) A antigen conjugate was allowed to bind to a living culture. The pRBC were counterstained with ethidium bromide and visualized by UV microscopy. (B) Sensitivity of rosetting (□) and A antigen conjugate binding by pRBC (●) of FCR3S1 cultures to trypsin treatment as indicated in Materials and Methods. (C) Competition of A antigen conjugate binding to living cultures by A-trisaccharide (■) and H-disaccharide (◊). All results shown are means ± SDs (error bars) from three separate experiments.

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