Mechanisms of hearing disturbance in an autoimmune model mouse NZB/kl.

A subline of the NZB mouse, NZB/kl, was found to develop severe hearing disturbances at high frequency sound at the age of 4 to 6 months. Deposition of IgG was observed on the capillary wall of the stria vascularis of the mice, but the concentration of circulating immune complex did not seem to be correlated to the deposition. Electron microscopic examination revealed that the capillaries had a thick basement membrane, and in severe cases the membrane contained foamy structures of various size. In some cases the base membrane was so thick that the capillary lumen was narrowed, and the intermediate cells seemed to be damaged. No pathological findings were found in other inner ear tissues. These results suggest that the changes in the stria vascularis were possibly caused by an autoimmune mechanism which resulted in hearing disturbance.