Concanavalin A Inhibition of Tissue Factor (Thromboplastin) Activity

Abstract

Abstract Studies with the jackbean lectin, concanavalin A, were undertaken to clarify the relationship between tissue factor and the cell membrane of cultured fibroblasts. Concanavalin A blocks the coagulant activity of tissue factor of cultured human skin fibroblasts and also rabbit brain. The inhibitory effect, which is dose-dependent and reversed by alpha-methyl-D-mannopyranoside, cannot be explained by an effect on other reactants necessary for clot formation. These results support the contention that tissue factor is located on the cell surface. Since concanavalin A does not affect adhesion-related phenomena in cultured cells, these results also suggest that tissue factor produced by trypsinized fibroblasts is a consequence rather than the cause of cell adhesion and that tissue factor is not synonymous with the adhesive site on the cell surface.