Induction of Endolymphatic Hydrops by Directly Infused Monoclonal Antibody against Type Ii Collagen CB11 Peptide

Autoimmune ear disease induced by type II collagen has been investigated by Yoo et al. In the present study, we investigated the effects of direct chronic infusion of type II collagen-specific monoclonal antibodies into guinea pig cochlea. Type II collagen fragment CB11 peptide-specific monoclonal antibodies (anti-CB11 Mabs) were infused directly into the scala tympani of guinea pigs with an Alzet mini-osmotic pump (anti-CB11 Mab group). As a control, normal mouse serum was infused by the same method (control group). To evaluate the auditory function, we recorded brain stem auditory-evoked potentials (BAEPs). In the anti-CB11 Mab group, 80% of the animals showed an increased hearing threshold of more than 25 dB at 7 days after infusion. The hearing threshold shift observed in the guinea pigs of the control group was minimal (15 dB or less). To detect the structural changes, we performed histopathologic studies using hematoxylin and eosin staining. Inflammatory cell migration was detected mainly in the scala tympani of the guinea pigs of both groups. In the anti-CB11 Mab group, endolymphatic hydrops was also observed. The results of this experiment suggest that type II collagen autoimmunity is responsible for the production of hearing loss and endolymphatic hydrops.