IMMUNOLOGICAL POTENTIAL OF THE TYMPANIC MEMBRANE - OBSERVATION UNDER NORMAL AND INFLAMMATORY CONDITIONS

Purpose: The immunological potential of the murine tympanic membrane w as studied under normal and inflammatory conditions. Materials and Met hods: Experimental otitis media was induced by injecting keyhole limpe t hemocyanin into the tympanic cavity of systemically sensitized mice. The animals were killed from 1 day to 2 weeks after the injection, an d the distribution of the immunocompetent cells in the tympanic membra ne was compared with those in normal animals, by immunohistochemical a nd toluidine blue staining. Results: Tympanic membranes under normal c onditions showed few immunocompetent cells, except mast cells and la-p ositive dendritic cells (presumably Langerhans' cells) in the pars fla ccida and in the annular and manubrial regions of the pars tensa. Afte r the induction of otitis media, lymphocytes migrated into these regio ns, although the other regions of the pars tensa showed few of these c ells. la-positive cells migrated into both pars tensa and pars flaccid a. Mast cells did not show obvious changes between the normal and infl ammatory conditions. Conclusion: The pars flaccida and the annular and manubrial regions of the pars tensa are considered to be the immunolo gically potential sites, responsible for the immune responses. The rem aining greater part of the tympanic membrane can recognize antigens by the migrated Langerhans' cells. Copyright (C) 1997 by W.B. Saunders C ompany.