An immunochemical quantitative analysis of the protein pattern in physiologic and pathologic vitreous

Biochemical changes in the vitreous in different vitreoretinal disorders have not yet been thoroughly studied. Using enzyme-linked immunosorbent analysis (ELISA), we established mean values and 95% confidence intervals for six proteins of physiologic human vitreous: albumin (293 +/- 18 mg/l), transferrin (73.7 +/- 6.6 mg/l), immunoglobulin G (IgG), (33.5 +/- 3 mg/l), alpha 1-antitrypsin (14.1 +/- 2.9 mg/l), alpha 1-acid glycoprotein (4 +/- 0.7 mg/l), and lactoferrin (less than 50 micrograms/l). These six proteins were also determined in vitreous aspirates from patients with idiopathic proliferative vitreoretinopathy (n = 10), traumatic proliferative vitreoretinopathy (n = 10), and proliferative diabetic retinopathy (n = 15). The pattern of protein levels varied widely within each of the disorders. An analysis of absolute protein levels showed significant differences in total protein and alpha 1-antitrypsin levels between controls and pathologic vitreous samples. We observed differences in transferrin between controls and proliferative diabetic retinopathy (PDR), and differences in alpha 1-acid glycoprotein between controls and both types of proliferative vitreoretinopathy (PVR). The single disorders themselves could not be differentiated by any of the proteins. When the relative contribution of single proteins to total vitreal protein was compared, albumin was lower in all three disorders than in controls. Transferrin was lower in traumatic PVR than in controls, in PDR, or in idiopathic PVR. Our results indicate that the three vitreoretinal disorders studied are characterized by a breakdown of blood-ocular barriers.