RETINAL AUTOANTIBODIES

JIRAWUTHIWORAVONG, GUY V.; LEVY-CLARKE, GRACE A.; NUSSENBLAT, ROBERT B.

Retinal autoantibodies, commonly referred to as antiretinal antibodies (ARA), have been implicated in the pathogenicity of a variety of immune-mediated visual disorders. In the paraneoplastic syndrome, cancer-associated retinopathy (CAR), ARA with their targeted retinal antigens have been identified. There are many other infectious, inflammatory as well as degenerative retinopathies associated with the presence of ARA. More than 15 ARA have been identified in CAR. For these autoantibodies, the autoantigens still remain unknown. Recoverin, a calcium-binding retinal protein involved in the reversal of the phototransduction cascade, is well established as the most common CAR autoantigen. The proposed mechanism of antibody-mediated degeneration involves molecular mimicry and loss of peripheral tolerance to residing retinal antigens. In vitro, ARA have been shown to cause apoptotic death of photoreceptors. Questions remain though, regarding the access and penetration of these antibodies into the retina. Furthermore, the titer of ARA does not always correlate with clinical disease status. There exists lack of standardization of antibody and antigen detection. Thus, results from different laboratories cannot exactly be compared. Sensitivity and specificity for the detection of pathogenic ARA is also lacking. Though there are many caveats, presence of ARA still serves as an adjunctive study for the clinician to confirm a diagnosis, which often is difficult to make. The study of ARA serves as an excellent model for the elucidation of pathological mechanisms underlying autoimmune retinopathy and its allied disorders.