Characterization of the Coagulant Activity of Cultured Human Fibroblasts

Skin fibroblasts were cultured from normal individuals, from patients with hemophilia, and from known and suspected carriers of hemophilia. All cell lysates studied had similar coagulant activity unaffected by incubation with a specific antibody to factor VIII and, therefore, presumably not factor VIII. Further investigation indicated that the coagulant had many properties indistinguishable from those associated with “tissue factor,” including heat lability, sedimentation characteristics, and dependency on factor VII for expression of coagulant activity. The presence of tissue factor in skin fibroblasts is consistent with the wide distribution of this coagulant, and the ability to maintain this material in tissue culture provides an opportunity for further investigation of the role of tissue factor in normal and pathologic states.