Possible role for cell-surface carbohydrate-binding molecules in lymphocyte recirculation.

Abstract

The hypothesis that carbohydrate-binding molecules on the cell surface are involved in the recirculation of lymphocytes from the bloodstream into lymphoid organs was investigated. This phenomenon requires the specific attachment of circulating lymphocytes to the endothelial cells of postcapillary venules. By used of an in vitro assay to measure the adhesive interaction between lymphocytes and postcapillary venules, it was found that L-fucose, D-mannose and the L-fucose-rich, sulfated polysaccharide fucoidin specifically inhibit this binding interaction. L-Fucose apparently shows stereo-selective inhibitory activity at concentrations > 18 mM, while fucoidin produces 50% inhibition at .apprx. 1-5 .times. 10-8 M. Fucoidin appears to interact with the lymphocyte and not the postcapillary venule, to inhibit binding. Cell surface carbohydrates (fucose-like) and carbohydrate-binding molecules (cell surface lectins) may contribute to the specific attachment of lymphocytes to postcapillary venules.