Autoimmune sensorineural hearing loss: a preliminary experimental study.

The aim of this study was to compare cochlear alterations produced by induction of anti-type II collagen antibodies with alterations produced by passive transfer of anticochlear antibodies. Guinea pigs (GP) were used. The anticochlear antibodies were obtained by injecting GP membranous cochlea plus Freund's adjuvant into rabbits. After partial purification of the immunoglobulins, the antibodies (20 mg) were injected intramuscularly into 10 normal GP. A second group of 10 normal GP received intramuscular injections of purified chicken type II collagen (1 mg) plus Freund's adjuvant. A control group of 10 normal GP was studied under the same conditions without any stimulus. The cochlea function was analysed with brainstem evoked audiometry (BERA). The structural study was carried out by immunofluorescent and hematoxylin preparations. The results showed structural alterations in both experimental groups (loss of nucleus in the spiral ganglion); however, significant changes in the BERA were not found. Only increase of the latency of wave I could be seen. These preliminary results support the hypothesis that antibodies to collagen type II may play an important role in human autoimmune sensorineural hearing loss, but the possible existence of other cochlear antigens is discussed.