Abstract
Based on diverse activities and production of several cytokines, T lymphocytes and T helper cells are divided into Th1, Th2, Th17 and regulatory T-cell (T regs) subsets based on diverse activities and production of several cytokines. Infectious agents can escape from host by modulation of immune responses as effector T-cells and Tregs. Thus, regulatory T-cells play a critical role in suppression of immune responses to infectious agents such as viruses, bacteria, parasites and fungi and as well as preserving immune homeostasis. However, regulatory T-cell responses can advantageous for the body by minimizing the tissue-damaging effects. The following subsets of regulatory T-cells have been recognized: natural regulatory Tcells, Th3, Tr1, CD8+ Treg, natural killer like Treg (NKTreg) cells. Among various markers of Treg cells, Forkhead family transcription factor (FOXP3) as an intracellular protein is used for discrimination between activated T reg cells and activated T-cells. FOXP3 has a central role in production, thymocyte differentiation and function of regulatory Tcells. Several mechanisms have been indicated in regulation of T reg cells. As, the suppression of T-cells via regulatory T-cells is either mediated by Cell-cell contact and Immunosuppressive cytokines (TGF-Beta, IL-10) mediated.
Highlights
The existence of regulatory T-cell was first suggested over two decades ago, but since a lot of questions about their structure and function remains unanswered
latency-associated peptide (LAP) as a marker be highly expressed on activated Tregs and platelets.(Howard L Weiner, da Cunha, Quintana, & Wu, 2011) Antigen presenting cells(APCs) induces Th3, this effect is amplificated by IL-4, IL-10 and TGFβ(Seder et al, 1998)
Many studies were showed that CD8+ regulatory cells expressed glucocorticoid-induced tumor necrosis factor receptor (GITR) and tumor necrosis factor receptor 2 (TNFR2), which were identified in human thymus(Cosmi et al, 2003)
Summary
The existence of regulatory T-cell was first suggested over two decades ago, but since a lot of questions about their structure and function remains unanswered These cells have the ability to regulate innate and adaptive immune responses, especially cellular immunity (Hasanjani et al, 2016; Ranjbar et al, 2012; Yazdani et al, 2015). Other markers of nTregs include OX40,CD62 ligand, CTLA4 and Forkhead family transcription factor (FOXP3), among them which only a high level of intracellular FOXP3 is a specific molecular marker for distinction between activated regulatory T-cells and other cells like activated CD4+ T-cells(Hori, Nomura, & Sakaguchi, 2003). A number of researches do not confirm this issue (Davidson, DiPaolo, Andersson, & Shevach, 2007)
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