[Cochlear immune injury following direct antigen challenge to the endolymphatic sac]

Following direct KLH antigen challenge to the endolymphatic sac (e. sac) in guinea pigs, degeneration of the cochlea was examined histologically by light microscopy. Degeneration was seen in 21 out of 140 animals presensitized systemically from day 1 to 5 weeks post secondary KLH challenge to the e. sac. Degeneration of the organ of Corti, stria vascularis and spiral ganglion cells was seen from day 1 in 19, 17 and 7 animals, respectively. There was no increase in these degenerative processes during the time course. In the period from day 1 to day 4, severe bleeding in the perilymphatic space occurred simultaneously with cochlear deterioration. Three animals showed perilymphatic fibrosis which was noted after the first week post KLH secondary challenge. In contrast, animals primarily challenged with KLH (locally administered to the e. sac) showed no cochlear degeneration. These results suggest that a locally mounted immune response in the e. sac can cause direct immune injury to cochlear tissues.