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.