Schistosoma mansoni egg attachment to cultured human umbilical vein endothelial cells: an in vitro model of an early step of parasite egg excretion.

To model the attachment of Schistosoma mansoni eggs to the endothelium of the mesenteric vasculature, the interaction between S. mansoni eggs and cultured human umbilical vein endothelial cells (HUVEC) in vitro was investigated. S. mansoni eggs rapidly attached to monolayers of both HUVEC and bovine aortic endothelial cells but more slowly to monolayers of cultured fibroblasts and smooth muscle cells. While both native and glutaraldehyde-fixed eggs attached equally well to HUVEC, eggs attached only to live, metabolically active HUVEC. Attachment was enhanced by both serum and plasma factors. In addition, platelet release products increased egg attachment by 75%. Preincubation of S. mansoni eggs with soluble egg antigens promoted attachment; in contrast, preincubation of HUVEC with the antigens inhibited attachment. These results suggest that interaction of S. mansoni eggs with HUVEC is an active process that can be modulated by molecules secreted by the egg and by platelets during egg extravasation.