Characterization of cytokine-producing cells in mucosal effector sites: CD3+ T cells of Th1 and Th2 type in salivary gland-associated tissues.

The major purpose of this study was to elucidate Th1 [interferon (IFN)-gamma and interleukin (IL)-2] and Th2 (IL-4, IL-5 and IL-6) cytokine-producing CD3+ T cells in salivary glands, which are the major mucosal effector tissues in the oral region. Thus, CD3+ T cells were isolated from salivary gland-associated tissues (SGAT) which consist of the submandibular gland (SMG: approximately 46%), the periglandular lymph node (PGLN: approximately 72%), and the cervical lymph node (CLN: approximately 90%). When SMG CD3+ T cells were examined by Th1 and Th2 cytokine-specific ELISPOT and reverse transcriptase-polymerase chain reaction assay, high levels of both cytokine-specific spot-forming cells (SFC) and mRNA for IFN-gamma, and for IL-5 and IL-6 were noted as representative Th1 or Th2 cytokines, respectively. Following stimulation with concanavalin A (Con A), SMG CD3+ T cells expressed mRNA and produced lymphokines for an array of Th1 (IFN-gamma and IL-2) and Th2 (IL-4, IL-5 and IL-6) cytokines. In comparison to the SMG CD3+ T cells, PGLN and CLN contain lower numbers of IFN-gamma-, IL-5 and IL-6-producing T cells. When these two tissues were compared, PGLN CD3+ T cells contained higher numbers of cytokine-secreting cells than CLN. Further, IL-2 and IL-4 SFC and mRNA were also noted in addition to IFN-gamma, IL-5 and IL-6 after Con A activation. These findings showed that CD3+ T cells in SGAT, especially the SMG, are programmed to produce IFN-gamma, and IL-5 and IL-6 as Th1 and Th2 cytokines, respectively in vivo, although these cells are capable of producing other Th1 and Th2 cytokines after receiving appropriate T cell activation signals.