Rosetting of Plasmodium falciparum required multiple components of the uninfected erythrocytes.

The mechanism of rosette formation of uninfected erythrocytes with Plasmodium falciparum-infected erythrocytes is rarely described. In this study, rosetting of uninfected normal erythrocytes with infected erythrocytes significantly reduced after treatment of the uninfected erythrocytes with neuraminidase. In contrast, the rosetting property of the infected erythrocytes was abolished by trypsinization but not by neuraminidase. The in vitro rosetting model showed that uninfected thalassemic erythrocytes poorly formed rosettes with infected normal erythrocytes when compared with normal erythrocytes of the same blood group. A rosetting parasite clone showed significant reduction in rosetting with thalassemic erythrocytes of all blood groups, however, this reduction was not obvious when the wild P. falciparum isolates were studied. These results suggest that while parasites from a single clone can rosette with uninfected erythrocytes via carbohydrate component, there is more than one type of receptor on uninfected erythrocytes involved in rosette formation with the heterogeneous populations of the wild P. falciparum isolates.