Endolymphatic hydrops induced by immune response of the endolymphatic sac: relation to perilymph antibody levels

This study investigated the effect of a secondary immune response in the endolymphatic sac on the development of endolymphatic hydrops in guinea pigs. Following secondary keyhole limpet hemocyanin (KLH) challenge directly to the sac in systemically presensitized animals, hydrops rapidly developed within 1 week, then gradually reduced by 4 weeks. After 5 weeks, hydrops gradually recurred and developed again. Mean perilymph anti-KLH antibody levels rose from day 1 to 4 weeks and then decreased. The elevation of perilymph anti-KLH antibody levels on day 2 was due to an increased vascular permeability and there was a local regeneration by the challenge of the sac after day 7. The development of hydrops correlated well with mean perilymph anti-KLH antibody levels in the period from day 1 to day 7. After 2 weeks, there was no correlation between them. These results suggest that an immune response of the sac may induce an excess secretion of endolymph in the initial stage and may further lead to irreversible dysfunction of the sac at a later stage.