Experimental autoimmune cystitis: further characterization and serum autoantibodies.

Previously, we described an animal model for interstitial cystitis (IC), experimental autoimmune cystitis (EAC) [Luber-Narod et al. Urol Res 24:367]. Further characterization of animals with EAC indicates that peak and mean urinary frequency are elevated compared with sham-injected controls and that the disease progresses with at least two cycles of exacerbations and remissions. We had shown evidence suggesting EAC to be autoimmune in nature. In this paper, we identify serum autoantibodies from 9/10 EAC animals which bind to a protein specific to rat bladder with a relative molecular weight of 12-kDa. Such autoantibodies are absent in 12/13 normal and sham-injected animals as well as animals which fail to develop EAC despite disease induction. These findings suggest that EAC is a reproducible model of cyclical increases of urinary frequency, and that a 12-kDa antigen is the target of autoantibodies which correlate with those elevations. Identification of this target antigen may explain the pathogenesis of increased urinary frequency in these animals and potentially in IC as well.