In our initial experiments, iTregs were generated by stimulation of naive T cells with plate-bound anti-CD3 in the presence of TGF. to naive responder T cells to generate pTregs. Manipulation of Treg function will require the ability to differentiate tTregs from pTregs and iTregs. Olodanrigan The expression of the transcription factor Helios has proven to be a useful marker for the identification of stable tTregs in both mouse and man. in the presence of TGF, and these should be termed by polyclonal tTregs and the mechanisms used by antigen-specific iTregs. Rabbit Polyclonal to SLC27A4 We also discuss the use of potential markers to distinguish tTregs from pTregs, as a detailed characterization of these subpopulations has important clinical implications for their use in cellular immunotherapy. Suppression of autoimmune disease by polyclonal tTregs The initial studies (4) describing the existence and functional properties of CD4+CD25+ Tregs demonstrated that they could prevent autoimmune diseases induced after transfer of CD4+CD25? T cells to immunodeficient recipients and also prevented induction of organ-specific autoimmunity that developed Olodanrigan after thymectomy on the third day of life (d3Tx). The majority of CD4+CD25+ T cells were later shown to express Foxp3 (5, 6). It has been widely assumed that the majority of freshly isolated Foxp3+ T cells are actually tTregs, although the contribution of pTregs to their activity cannot be excluded due to the lack of a reagent that would allow definitive separation of tTregs from pTregs. Nevertheless, for the purposes of this review, we assume that the majority of the suppressive activity of freshly isolated Foxp3+ T cells from normal unmanipulated mice is mediated by tTregs and not by a small percentage of autoantigen-specific pTreg cells. Although the ability of tTregs to inhibit organ-specific autoimmune disease has been well documented, the mechanisms underlying their suppressive functions remain poorly characterized. We have used autoimmune gastritis (AIG) as the model for analyzing the suppressive properties of tTregs (7). One advantage of this model is that it is one of the few models of spontaneous organ-specific autoimmune disease in which the target antigen, the proton pump of the gastric parietal cell, the H/K ATPase, has been defined (8). We have generated T-cell receptor (TCR) transgenic (Tg) mice expressing TCRs derived from T-cell clones isolated from the gastric lymph nodes of d3Tx mice with AIG (9, 10). One of these TCR-Tg strains (TxA23) spontaneously develops AIG early in life and the effector cells express a T-helper 1 (Th1) phenotype. Low numbers of CD4+CD8?Foxp3? thymocytes from TxA23 mice will readily transfer disease to recipients. We examined the effects of polyclonal tTregs in this cell transfer model in which the target antigen is expressed and presented at physiological levels. Although the co-transfer of polyclonal tTreg prevented the induction of AIG, it did not prevent the migration of autoantigen-specific T cells to the gastric lymph node or the stomach, nor did it prevent their expansion. Thus, the primary effect of polyclonal tTregs appeared to be inhibition of the differentiation of the autoantigen-specific T cells into pathogenic Th1 cells as reflected by a decrease in antigen-stimulated interferon (IFN) production by the Olodanrigan transferred TxA23 cells isolated from treated recipients (7). We have also used polyclonal populations of tTregs to address whether tTregs could suppress AIG induced by fully differentiated Th1, Th2, or interleukin-17 (IL-17)-secreting autoantigen-specific T effector cells (11). One additional goal of these studies was to determine whether polyclonal tTregs could modulate cytokine production by fully differentiated effector cells from CD4+CD8?Foxp3? TxA23 thymocytes and all three T helper cell types transferred AIG into recipients. Each type of T-effector cell induced AIG with distinct histological patterns. Th17 cells induced the most destructive disease. Polyclonal tTregs could suppress Olodanrigan the capacity of Th1 cells, moderately suppress Th2 cells, but could only minimally suppress Th17-induced disease. The major effects of the tTregs were related to their ability to inhibit T-effector cell expansion, as tTregs significantly reduced the total number of injected T-effector cells in the.