Detection of inner ear disease autoantibodies by immunoblotting

To define further the character of autoantibodies against the inner ear in patients with inner ear disease, Autoantibodies in sera from 82 patients with inner ear disease were investigated by immunoblotting. The inner ear antigens were extracted from Hartley guinea pigs. Brain, kidney, lung, heart and liver extracts were also prepared. Antibodies against the inner ear were found in 32 of 82 (39%) patients with inner ear disease. These sera reacted with the 30 and 58 kDa bands of the inner ear extracts. The 30 kDa band was detected in sera from patients with various inner ear diseases, while the 58 kDa band reacted with sera of patients with idiopathic progressive sensorineural hearing loss. Only two of the 52 normal control sera had a very faint band at 30 kDa. Sixteen of 32 positive sera were then used to probe Western blots of the brain, kidney, lung heart and liver extracts. The 58 kDa band was also found in the protein extracts of the brain, the lung, and the liver. On the other hand, preliminary purification of the 30 and 58 kDa proteins from the inner ear extracts were achieved by anion exchange chromatography. These results show that antibodies in sera from patients with inner ear disease reacted with at least two polypeptide bands (30 and 58 kDa) of guinea pig inner ear extracts, and the 58 kDa antigenic epitope was not cochlea specific.