Immunofluorescent localization of factor VIII-related antigen, fibrinogen, and several other plasma proteins in hemostatic plugs in humans.

Factor VIII-related antigen and its low ionic strength subunits were demonstrated in endothelium and hemostatic plugs obtained from punch biopsies of bleeding time wounds according to Mielke. No IgG, IgA, IgM, C4-C3, albumin, or prothrombin was demonstrated in the cryostat sections of hemostatic plugs. Antifibrinogen stained the hemostatic plug and fibrin fibers along the edges of the skin wound. Antiplatelet actomyosin stained the hemostatic plug and the endothelium and pericytes of blood vessels. These results suggest that factor VIII is present in the hemostatic plug not by trapping of plasma but by close association with or presence within the blood platelets. The positive staining of a hemostatic plug in which most platelets have undergone the release reaction indicates that antifactor VIII may be useful for the detection of platelet thrombi in tissue of patients with suspected diffuse intravascular coagulation.