IgA immunocytes in tonsils.

Dimeric IgA-forming cells were studied by a secretory component (SC) affinity test on 20 palatine and 7 pharyngeal tonils from children. This study also included an investigation on the immunoflurescent localization of IgA immunocytes and IgA and SC deposits. The results showed that IgA immunocytes capable of binding SC in tissue sections are present in both palatine and pharyngeal tonsils. However, the number of cells positive for the SC affinity test was significantly lower than that of IgA immunocytes not binding SC. IgA immunocytes were located mainly in the subepithelial area, medullary portion, and occasionally the intraepithelial layer. SC determinants were detected only in some epithelial cells of the pharyngeal tonsils. The findings of the present study suggest that the pharyngeal tonsils share in the local immunological mucosal resistance regulated by secretory IgA, although its activity might be limited.