The significance of complement in proliferative vitreoretinopathy

Complement is the principal effector arm of antibody-mediated allergic response and plays a central role in the pathogenesis of many immunologic disorders. The possible pathophysiologic importance of complement was examined in the development of proliferative vitreoretinopathy (PVR). Vitreous aspirates from patients with idiopathic PVR (n = 21) and traumatic PVR (n = 15) were examined for total vitreal protein (TVP) and complement components C3, C3d, C4, and C1q-fixed immunoglobulins using enzyme-linked immunosorbent assay (ELISA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and western blotting. The TVP, C3 components, and factor C4 were elevated significantly in diseased vitreous. The C3-TVP and C4-TVP ratios showed no difference between traumatic and idiopathic PVR. A C4 index to estimate the rate of intraocular C4 synthesis had a mean value of 3.2 (n = 15). The increased relative amount of C3d reflected complement activation in diseased vitreous. The negative values in normal human serum and plasma and in patient plasma samples (n = 15) indicated a local reaction in the eye. The authors found C1q-fixed immunoglobulin G; this may be the cause of complement activation by the classic pathway. These findings support the opinion that the cause of PVR may be based partly on an autoimmune reaction against ocular structures.