Retinal ganglion cells recognized by serum autoantibody against gamma-enolase found in glaucoma patients.

PURPOSE: To study pathologic roles of the presence of serum autoantibodies against retinal ganglion cells in patients with glaucoma.

METHODS

Serum autoantibody reactions were detected by Western blot analysis using retinal soluble fractions in 79 patients with glaucoma (normal-tension glaucoma [NTG], 23 cases; primary open-angle glaucoma [POAG], 56 cases) and 60 age-matched healthy subjects. Clinical characteristics including visual acuity, visual field, intraocular pressure (IOP), and optic disc features were compared between the serum autoantibody-positive and -negative patients. The retinal autoantigen recognized by patients' sera was identified by a combination of in-gel digestion and Edman sequencing.

RESULTS

Western blot analysis revealed that serum autoantibody against retinal 50-kDa antigen was recognized in 20 out of 79 glaucoma patients (25.3%; 14 POAG and 6 NTG patients) and 60 age-matched control subjects (11.7%), respectively. Immunocytochemistry revealed that labeling of the ganglion cell layer (GCL) by IgG from glaucoma patients (POAG: 13/56, 23.2%; NTG: 6/23, 26%) existed at a significantly higher rate than that by IgG from control subjects (2/60, 3.3%; P < 0.05). In POAG, maximum IOP in the serum antibody positive-patients was significantly lower than that in the antibody-negative patients (P < 0.05). However, no statistical differences were observed in visual field loss, disc cupping, and other clinical factors between the antibody-positive and -negative groups in POAG and NTG. In-gel digestion of the 50-kDa band in two-dimensional polyacrylamide gels and Edman sequence analysis of the high-performance liquid chromatography-purified peptides identified the 50-kDa protein as gamma-enolase. Injection of the 50-kDa IgG from glaucoma patients or anti-gamma-enolase serum into the vitreous cavity of Lewis rats caused reduction of the b-wave of the electroretinogram and TdT-dUTP terminal nick-end labeling (TUNEL)-positive staining within the GCL.

CONCLUSIONS

In the current study, serum autoantibody against 50-kDa protein identified as gamma-enolase in 25% of glaucoma patients.