Role of gamma delta-T cells in the palatine tonsil

Gamma delta-T cells in the tonsil were evaluated by flow cytometric analysis and immunohistological study using monoclonal antibodies to the gamma delta-T cell receptor. Flow cytometric analysis using TCR-gamma/delta-1 showed that 2.2%, of T cells in the tonsil obtained from patients with recurrent or chronic tonsillitis expressed the gamma delta-T cell receptor. Immunohistologically, gamma delta-T cells were found mainly in the extrafollicular area, i.e., the T-cell zone, and showed strong migration to the crypt epithelium in tonsils with infections. The comparison on number of gamma delta-T cells in cases with simple hypertrophic tonsil and in cases with recurrent or chronic tonsillitis showed that tonsils with repeated or chronic infections had a significantly greater number of gamma delta-T cells than tonsils without infection. To address the functional aspects of gamma delta-T cells in the tonsil, the production of IL-2 of separated gamma delta-T cells was measured by solid phase ELISA. Increased IL-2 production was observed with staphylococcal enterotoxin A and B stimulation, and this increase was blocked by antibody to the gamma delta-T cell receptor, indicating that the production of IL-2 may be triggered by the interaction between the gamma delta-T cell receptor and staphylococcal enterotoxin. Our results show that gamma delta-T cells in the tonsil, especially in the crypt epithelium, may be activated by various bacterial antigens or heat shock protein released from damaged epithelial cells. The activated gamma delta-T cells will produce cytokines including IL-2 and function as so-called 'first-layer' immunity.