Crude inner ear antigen (CIEAg) can induce autoimmune inner ear disease (AIED) although it is not known which subcomponent of CIEAg is involved. In this study, we investigated the relationship between 3 puried inner ear antigens (31, 42-45 and 60kD proteins) and AIED, and determined their distribution in normal guinea pig cochlea. Three groups of guinea pigs were immunized with the three inner ear antigens and one group served as a control. The hearing thresholds, serum IgG level and morphological changes in the inner ear were observed. The expression of the three antigens in the cochlea was detected using immunohistochemical techniques. No obvious changes in hearing thresholds or inner ear morphology were observed between the control and 42-45kD groups. Animals immunized with the 31 or 60kD proteins showed a signi cant increase in hearing thresholds (p B 0.05 vs control), accompanied by morphological changes in the inner ear. The serum IgG level was increased signi