Abstract
Purpose: :
To investigate whether autoimmune retinopathy (AIR) patients with abnormal photopic electroretinogram b-wave amplitudes have anti-retinal antibody activity against cones by indirect immunohistologic techniques.
Methods: :
A larger group of AIR patients were screened for individuals who had abnormal (reduced) photopic electroretinograms (ERGs) detected by standardized ISCEV methodology. Twenty-nine patients were randomly selected who had at least four anti-retinal antibody immunoreactive bands on standard Western blots and abnormal photopic ERGs. erum from these patients and six controls were placed on frozen normal human retina sections. These were embedded in optimum cutting temperature compound and were blocked for nonspecific protein binding with 5% goat serum in a phosphate-buffered saline (PBS) solution for 1 hour, and incubated with serum from the AIR patients (dilution, 1:500) overnight at 4°C. After washing with PBS plus 0.2% Triton X-100 (3 times at room temperature for 10 minutes each), the sections were incubated with Alexa Fluor 488-conjugated anti-goat IgG secondary antibody (dilution, 1:2000), and counterstained with 0.3µM DAPI before slides were examined with a confocal fluorescence microscope. Co-localization was performed with anti-M opsin antibody.
Results: :
Twenty-seven of 29 patients had clear cone staining on immunohistology from this selected group. Normal control sera were negative. Anti-M opsin antibody co-localized to the same cone photophotoreceptors that were stained by the patients’ antibodies. Clinically the patients had typical findings of autoimmune retinopathy: abrupt onset with photopsias, no family histories of cone or retinal dystrophy, no pigmentary deposits, variably abnormal electroretinograms, but with all patients having abnormal photopic ERGs. About one-half of patients had 15-20o central scotomata on Goldmann visual fields.
Conclusions: :
This preliminary investigation suggests that abnormal photopic ERGs in AIR patients are associated with anti-cone photoreceptor antibodies. These antibodies are associated with abnormal visual acuities and central scotomata and can be detected by the above laboratory methods. Measuring these antibodies gives a defined target for assessing treatments with immunosuppression in this AIR patient group who have anti-cone autoantibodies.
Keywords: autoimmune disease • retinal degenerations: cell biology • photoreceptors