DISTRIBUTION OF KHRI-3 EPITOPES IN THE INNER-EAR

Murine monoclonal antibodies against cochlear structures were previous ly generated to obtain probes for elucidating the function of cochlear cell subsets. Preliminary immunocytochemical characterization showed that the monoclonal antibody KHRI 3 binds to supporting cells but not sensory cells in the guinea pig cochlea. We have now investigated KHRI 3 epitopes in other species and other parts of the inner ear. The KHR I 3 epitope appears to be species-specific since no immunolabeling was seen in rat inner ear nor in chick inner ear. In immunocytochemical a ssays in. the guinea pig vestibular tissues KHRI 3 stained saccular wa ll cells and transitional epithelial cells in the utricle and ampules as well as clusters of cells in the endolymphatic sac. In Western blot s KHRI 3 stained a broad 70-75 kDa band in lanes loaded with guinea pi g cochlea homogenates - as seen previously - as well as in lanes loade d with vestibular tissue homogenates. The immunolabeling patterns sugg est that KHRI 3 epitopes are cell membrane components or related to me mbrane structures. Thus the monoclonal antibody KHRI 3 appears to defi ne a nonsensory cell subset in the guinea pig inner ear that can be id entified by expression of KHRI 3 epitopes.