Cell adhesion molecules of experimental otitis media in the rat.

We examined the expression of cell adhesion molecules (CAM) in immune-mediated otitis media using keyhole limpet haemocyanin (KLH) in the rat, as well as the regulation of these CAM in peripheral blood polymorphonuclear leucocytes (PMN) and lymphocytes upon exposure to middle ear effusion (MEE). After general immunization, a topical antigen was introduced into the middle ear cavity. One day after exposure, CD18+ cells, primarily PMN, had maximally invaded the middle ear mucosa and mucosal epithelium. Mucosal epithelium strongly expressed intercellular adhesion molecule-1 (ICAM-1), only on the first day. The total number of cells in MEE reached a peak on day 3. On day 3, ICAM-1+ cells had reached a peak of 24.5% of the total cells. On day 2. CD18+ cells had reached a peak at 75.3% of the total cells. We examined the regulation of CAM in peripheral blood upon exposure to MEE. The percentage of fluorescent CD18+ PMN increased with MEE compared to those incubated in its absence, but those of L-selectin-positive PMN significantly decreased CAM on the surface lymphocytes did not change when incubated with MEE. The expression of CAM (CD18, ICAM-1) appears important for the initiation of otitis media. Moreover, it was thought that the interaction between the infiltrated PMN and MEE may modify the expression of CAM during the inflammatory process in the middle ear cavity.