Am J Clin Exp Immunol 2013;2(1):94-106

Review Article
Regulatory T cells vs Th17: differentiation of Th17 versus Treg, are the
mutually exclusive?

Song Guo Zheng

Division of Rheumatology and Immunology, Department of Medicine, University of Southern California, Keck School of
Medicine, Los Angeles, CA. 90033, United States

Received February 14, 2013; Accepted February 22, 2013; Epub February 27, 2013; Published March 9, 2013

Abstract: Naive CD4+ cells differentiate into T helper (Th1, Th2, Th9, Th17) and regulatory T (Treg) cells to execute their
immunologic function. Whereas TGF-β suppresses Th1 and Th2 cell differentiation, this cytokine promotes Th9, Th17
and Foxp3+ regulatory T cells depending upon the presence of other cytokines. IL-6 promotes Th17, but suppresses
regulatory T cell differentiation. Moreover, natural but not TGF-β-induced regulatory T cells convert into Th17 cells in the
inflammatory milieu. Here an update of T cell differentiation and conversion, as well as underlying mechanisms are
given. (AJCEI1302001).

Keywords: T helper cells, Th1, Th2, Th9, Th17, Tfh, Foxp3+ regulatory T cells, cytokine, differentiation, autoimmunity

Address correspondence to: Song Guo Zheng, USC Keck School of Medicine, 2011 Zonal Ave., HMR 710A, Los
Angeles, CA 90033. Phone: 323-442-2128; Fax: 323-442-2874; E-mail:
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