Analysis of human corneal IgG by isoelectric focusing

Parameters which regulate the localization and retention of IgG within the corneal stroma are complex and poorly understood. Although multiple factors are involved, electrostatic interactions between IgG and anionic corneal tissue components, ie, proteoglycans (PG) and glycosaminoglycans (GAG) may regulate the distribution of antibodies within the corneal stroma. Isoelectric focusing (IEF) and blotting analysis of IgG revealed a restricted pI profile for both central and peripheral regions of the normal cornea. Similar analysis of pathological corneas from keratoplasty specimens in Fuchs' dystrophy and keratoconus reveal a variable IEF profile. In the majority of keratoplasty specimens from patients with corneal edema or graft rejection, there was generally little or no IgG detectable. These results suggest that in edematous corneas where there is altered PG/GAG in the stroma and modified fluid dynamics, there is a concomitant loss of IgG. These findings may have implications for immunologic surveillance and protection of the avascular cornea.