Procoagulant Synthesis by Cultured Fibroblasts triggered by Cell Adhesion

Abstract

SYNTHESIS of a potent procoagulant by cells in tissue culture has been demonstrated but its identity is obscure¹. Activity is low at the beginning of culture of normal human fibroblasts and increases several hundred-fold after 12–24 h of incubation at 37° C. This increase is readily detected by the one-stage assay for factor VIII (antihaemophilic globulin) but can also be demonstrated by the two-stage factor VIII assay based on the thromboplastin generation test. Studies in progress to characterize this procoagulant have demonstrated a marked increase of factor XI as well as factor VIII activity and evolution of factor XI activity during contact activation with celite. Increase in activity detectable in the one-stage assay for factor IX and XII was much less. The procoagulant was incapable of clotting a fibrinogen solution and no change in assays for factor V and VII was observed during culture.