[Detection of coagulation factor XIII in the vitreous body and periretinal membranes in proliferative retinal diseases].

The human blood coagulation factor catalyses the cross-linking of fibrin monomers at the end of the coagulation cascade. Additional functions are the coupling of fibronectin and collagen to each other and fibrin. Therefore we tried to investigate the significance of factor XIII in the development of intraocular membranes. Using gel electrophoresis and western blotting, both subunits (A and B) of factor XIII could be detected in vitreous aspirates from patients with "idiopathic" proliferative vitreoretinopathy (PVR) (n = 5), traumatic PVR (n = 5), and proliferative diabetic retinopathy (n = 5). In contrast the vitreous of five human "normal" post mortem eyes did not contain the subunits of factor XIII. Furthermore, we observed immunofluorescence staining for both subunits of factor XIII in 20 surgically obtained periretinal membranes. In early cellular as opposed to late hypocellular membranes we observed stronger labeling for both subunits of factor XIII. With double label staining techniques, the fibroblastic cells recognized by vimentin staining did not contain factor XIII. About 50% of the macrophages stained positive for the A-subunit of factor XIII. We observed no labeling for the B-subunit in macrophages. Therefore, we hypothesize that factor XIII in proliferative vitreoretinal disorders (PVR, PDR) is derived from the exudation of plasma and platelets through disrupted blood-retinal barriers.