Binding of Plasmodium falciparum-infected erythrocytes to soluble plateletendothelial cell adhesion molecule-1 (PECAM-1/CD31): Frequent recognition by clinical isolates

Plate let-endothelial cell adhesion molecule-1 or CD31 (PECAM-1/CD31) is a receptor recognized by Plasmodium falciparum-parasitized erythrocytes (pRBC s), Fluorescence-labeled soluble recombinant PECAM-1/CD31 (sPECAM-1/CD31) i s shown to bind to the surface of P. falciparum-infected erythrocytes on up to 70% of the cells. Binding is blocked by the addition of the unlabeled r eceptor in a dose-dependent fashion, but not by unrelated receptor-proteins , A significant correlation was found between the binding of sPECAM-1/CD31 to pRBCs and the binding to transfected L cells expressing the receptor as seen with six different P. falciparum lines or clones. Panning of cultures on PECAM-1/CD31 transfected L cells was paralleled by an increase in the bi nding of sPECAM-1/CD31. The pRBCs of 54% of fresh patient-isolates bound sP ECAM-1/CD31 with a mean rate of 12.9% (range = 1.1-44%). The data suggest t hat PECAM-1/CD31 is a common receptor recognized by wild isolates and that the soluble PECAM-1/CD31 suspension assay is a sensitive and reliable way t o study PECAM-1/CD31 binding.