Abstract
Purpose::
To determine the frequency of autoantibodies to cellular retinaldehyde binding protein (CRALBP), a novel retinal autoantigen, in human autoimmune uveitis patients.
Methods::
Recently we have identified CRALBP as a novel autoantigen in spontaneous equine recurrent uveitis (ERU), a model for human autoimmune uveitis. About 30% of ERU cases have autoantibodies and/or autoreactive T cells specific for CRALBP. Furthermore, CRALBP induced uveitis with incidences of 89% in Lewis rats and 100% in horses. In order to investigate a possible impact of CRALBP immunity on human uveitis we have tested the frequency of CRALBP autoantibodies in human uveitis patients and healthy donors. 5 µg/ml LPS free, recombinant human CRALBP was coated to enzyme linked immunosorbent assay plates (Nunc Maxisorp). Sera were diluted 1:4000 in PBS-T. A monoclonal, anti-human CRALBP antibody (Cayman) was used as a positive control. Binding of human sera to CRALBP was visualized with an anti-human-IgG-POD antibody and TMB detection. Frequencies of CRALBP autoantibodies in uveitis and control group were determined and compared using the chi-square test.
Results::
Twenty-four out of 51 human sera from uveitis patients (47%) were tested positive for anti-CRALBP autoantibodies compared to 1 out of 27 healthy controls (3,7%) using indirect enzyme linked immunosorbent assay (ELISA). Frequency of CRALBP autoantibodies was significantly more prevalent in human uveitis patients than in healthy controls p<0.001).
Conclusions::
The high frequency of autoantibodies to the novel autoantigen CRALBP points to a potential role of anti-CRALBP immune response in human autoimmune uveitis, as already shown for spontaneous equine recurrent uveitis. This autoantigen merits further investigations.
Keywords: uveitis-clinical/animal model • autoimmune disease