2G). regulatory system to regulate tissues and autoimmunity irritation. The disease fighting capability must distinguish not merely between self and nonself, but also between pathological and innocuous foreign Ags to avoid unnecessary or self-destructive defense replies. Unresponsiveness to self-Ags is set up through peripheral and central procedures. Whereas clonal anergy and deletion are systems of peripheral tolerance, energetic suppression by regulatory T cells (Tregs)3 provides emerged as an important element in the control of self-reactive cells. Two essential classes of Tregs inside the Compact disc4+ subset are CD4+CD25+Foxp3+ Tregs and T regulatory type 1 (Tr1) cells (1C4). These two regulatory subsets differ in a number of biological features, including their cytokine profile, cellular markers, transcription factors, and mechanism of immune suppression. Tr1 cells are CD4+ T lymphocytes defined by their production of IL 10 and suppression of helper T cells (5). Tr1 cells are inducible cells, arise from naive precursors, and can be differentiated both ex vivo and in vivo. Stimulation of human CD4+ T cells with allogeneic monocytes or murine CD4+ T lymphocytes with Ag, particularly in the presence of IL-10, leads to the generation of Tr1 clones (4). In addition, Tr1 cell differentiation has also been induced by dexamethasone and vitamin D3 (6). Finally, CD46 activation of T cells in the presence of IL-2 leads to Tr1 differentiation characterized by a massive secretion of IL-10 and bystander CD4+ T cell suppression (7). Altered function of Tr1 cells in Dihydrocapsaicin the human autoimmune disease condition multiple sclerosis has been reported, implicating the function of this subset in regulation of human autoimmune disease (8). Contrary to the function of Tr1 cells, Th 17 cells are known to have potent proinflammatory functions. Th17 cells belong to a recently identified Th subset, in addition to the traditional Th1 and Th2 subsets. These cells are characterized as preferential suppliers of IL-17. Th17 cells and their effector cytokines are associated with the pathogenesis of several human inflammatory and autoimmune diseases including multiple sclerosis, rheumatoid IGF1 arthritis, systemic lupus erythematosus, and psoriasis (9, 10). In mice, TGF-and IL-6 or TGF-and IL-21 have been shown to induce the differentiation of naive mouse T cells toward the Th17 phenotype (11C14). The differentiation of Th17 cells that secrete IL-17 (IL-17A) requires the expression of transcription factor retinoid orphan nuclear receptor (RORin combination with other proinflammatory cytokines (IL-1(50 ng/ml), IL-6 (50 ng/ml), IL-21 (25 ng/ml), IL-23 (25 ng/ml), TGF-(Fig. 1, A and B). By contrast, IL-27 stimulation inhibited anti-CD3 and anti-CD28 induced Dihydrocapsaicin IL-17 without affecting TGF-production (Fig. 1, C and D). Neither stimulatory condition induced IL-4. The transcription factors T-bet, GATA-3, RORC, and Foxp3 are required for the generation of Th1, Th2, Th17, and Treg cells, respectively. We found that cells stimulated with anti-CD3 and anti-CD28 induced expression of mRNA encoding Foxp3, GATA-3, T-bet, and RORC. Addition of IL-27 to the above culture condition greatly reduced the expression of GATA-3 and RORC, whereas the expression of T-bet and Foxp3 transcripts were not affected (Fig. 1, ECH). These observations suggest that IL-10 production induced by IL-27 did not depend on GATA-3, a transcription factor required for the generation of Th2 cells (36) and that IL-27-stimulated T cells have a cytokine profile that is distinct from that induced by stimulation with Abs to CD3 and CD28 but comparable to that of Tr1 cells. Open in a separate window Physique 1 IL-27 stimulation induces IL-10 production from human peripheral blood CD4+ T cells. ELISA of total CD4+ T cells stimulated with plate-bound anti-CD3 and anti-CD28 in the presence or absence of recombinant human IL-27 (100 ng/ml). and production. and production. in response to IL-27 stimulation (Fig. 2B). Consistent with IL-10 secretion, naive CD4+ T cells expressed more IL-27 receptor on their surface (Fig. 2C). In addition, we found that IL-27 did not affect the proliferation of either naive or Dihydrocapsaicin memory CD4+ T.