Lymphocyte-mucosal interaction of the middle ear mucosa

The middle ear mucosa possesses immunologic features similar to those of the peripheral mucosa sites in the common mucosal immune system and after mucosal immunization, antigenspecific IgA-forming cells appear in the inflamed mucosa of the tympanic cavity. Recent investigations suggest that lymphocyte migration to lymphoid tissues is regulated by lymphocyte-high endothelial venules (HEV) interaction. However, the lymphocyte migration mechanism to the middle ear mucosa is still unclear. We investigated whether or not organ-specific determinants which lymphocytes bind with are present on the middle ear mucosa by in vivo and in vitro lymphocyte adherence assays by using fluorescein-labeled lymphocytes from various lymphoid tissues. Many lymphocytes from Peyer's patches and hilar lymphnodes adhered on the inflamed middle ear mucosa with or without mucosal immunization, while these cells were not found on the normal tympanic mucosa. The number of the cells was smaller than that in the gastrointestinal mucosa. Lymphocyte adherence to the middle ear mucosa was not suppressed by anti-T cell antibody. These findings suggest that the middle ear mucosa possesses organ-specific mucosal determinants which B-lymphocytes selectively bind with, and that those determinants which regulate lymphocyte migration to the middle ear mucosa differ from those of other mucosae in the gastrointestinal tract.