Nasopharyngeal tonsil's provision of the surface secretions with immunocytes, a property additional to antigen processing.

As we recently found that IgA, IgM, and IgG are produced and secreted by immunocytes present in nasopharyngeal secretions, we tested the hypothesis that B- and T-lymphocytes in the surface secretions are derived from the nasopharyngeal tonsil in an active process. By immunohistochemistry, we found that numerous B- and T-lymphocytes were often accumulated in restricted areas in the epithelium, and some of these cells were demonstrated just beneath the epithelial surface or could be observed protruding into the lumen. A portion of these cells were Ki-67+, indicating clonal expansion and/or immunoglobulin class switching. Analyses of the surface secretions by immunocytochemistry also demonstrated B- and T-lymphocytes, as well as Ki-67+ cells--a finding that indicates that immunologically active cells are transported into the surface secretions. The results imply that there is a substantial migration from the nasopharyngeal tonsil of immunologically active cells into the surface secretions.