[Qualitative detection of immunoglobulins in the human endolymphatic sac]

Healthy human temporal bones and samples of the endolymphatic sac taken during surgery or from fresh cadavers were studied with regard to the presence of immunoglobulins. For demonstration of IgG, IgM, IgA and SIgA immunofluorescent methods and the immunoperoxidase-antiperoxidase method were used. Immunoglobulins are exclusively present within the endolymphatic sac whereas other structures of the healthy human inner ear do not show any positive reaction to the methods used for the demonstration of immunoglobulins.SIgA is clearly shown in epithelial cells of the rugosal part, whereas IgG predominantly is located in the flat endothelium--like cells of the extratemporal part. IgA and IgG further are detected within glycoproteins of the sac lumen and in plasma cells beneath the epithelium. Finally all subepithelial lymphatic spaces contain rich amounts of IgG. In one single temporal bone with tympanogenic labyrinthitis IgG and IgM wee present not only in all three layers of the round-window-membrane but also within the perilymphatic exudate. In this case IgM was found in the perisaccular tissue. The presence of free and local bound immunoglobulins exclusively in the region of the endolymphatic sac postulates and immunologic defense mechanism of this organ for the inner ear.