Schistosoma mansoni: In vitro adhesion of parasite eggs to the vascular endothelium. Subsequent inhibition by a monoclonal antibody directed to a carbohydrate epitope

Schistosoma mansoni eggs come into direct contact with the vascular endothe lium, particularly in the postcapillary venules of the mesenteric tract (ov iposition site). We investigated the adhesion of eggs to endothelial cells ina static in vitro assay and in a now-based in vitro assay. Live S. manson i eggs rapidly attached, in a time-dependent manner, to the human endotheli al cell Line ECV 301, but not KOH-treated eggs. Activation of ECV monolayer s with interleukin-1 promoted live S. mansoni eggs adhesion. An in vitro fl ow-based assay of human umbilical vein endothelial cells (HUVEC) showed the influence of wall shear stresses on the attachment of eggs to endothelial cells, particularly under postcapillary venule shear stress conditions. Int erleukin-1 activation of HUVEC promoted adhesion between Live eggs and endo thelial cells. Higher wall sheer stresses were needed to obtain the detachm ent of eggs from activated endothelial cells than control cells. Preincubat ion of interleukin-1-activated HUVEC, in a static in vitro assay, with mono clonal antibodies specific for intercellular adhesion molecule-1, E-selecti n, and vascular cell adhesion molecule-1 significantly decreased adhesion o f live eggs. Previous studies have shown that a monoclonal antibody specifi c for a schistosome carbohydrate epitope abundant in eggs is related to the Lewis X antigen. In this study, the anti-Lewis X-specific monoclonal antib ody was used for adhesion-inhibition assays. Preincubation of eggs with thi s monoclonal antibody significantly decreased adhesion of live eggs to inte rleukin-1-activated HUVEC cultured in vitro. These results suggest that sur face adhesion molecules, expressed by endothelial cells under conditions of interleukin-1 activation, directly participate in egg adhesion and that eg g carbohydrate antigens play an important role in live S. mansoni egg adhes ion to the vascular endothelium. (C) 1999 Academic Press.