Serum autoantibody against glutathione S-transferase in patients with glaucoma

To identify retinal proteins that are the targets of serum autoantibodies in patients with glaucoma.

To identify retinal antigens that are recognized by the sera of patients with glaucoma, immunoreactive bands were separated, by using two-dimensional gel electrophoresis of the bovine retinal soluble fraction. A 29-kDa band was then selected for further analysis. Tryptic peptides of the 29-kDa band were analyzed using electrospray mass spectrometry to identify the protein. After protein identification, immunoreactivity against this newly identified protein was studied by Western blot analysis using sera from 65 patients with glaucoma (25 with primary open-angle glaucoma [POAG]; 40 with normal-pressure glaucoma [NPG]) and 25 age-matched healthy subjects. In addition, serum antibody titers were compared in these groups, by using a specific enzyme-linked immunosorbent assay (ELISA).

The 29-kDa band was identified as glutathione S-transferase (GST). Western blot analysis revealed that serum antibodies against GST antigen were recognized in 34 (52%) of 65 patients with glaucoma (22 of NPG and 12 of POAG) and 5 (20%) of 25 age-matched control subjects (chi(2) test, P < 0.05). By ELISA, it was also found that patients with glaucoma had higher titers of anti-GST antibody, compared with the control group (Mann-Whitney test; NPG versus control, P = 0.013; POAG versus control, P = 0.0006).

These findings indicate that GST is one of the retinal antigens targeted by the serum antibodies detected in some patients with glaucoma.