发布: 2019年08月20日第9卷第16期 DOI: 10.21769/BioProtoc.3335 浏览次数: 3988
评审: Alka MehraChris TibbittAnonymous reviewer(s)
Abstract
Thymic Treg cell differentiation occurs via a two-step process. Step one generates Treg cell progenitors (TregP) and is driven by strong TCR interactions with antigens presented in the thymus. Step two is initiated by activation of STAT5 via IL-2, or IL-15, leading to mature Treg cells capable of emigrating from the thymus and mediating immune tolerance and homeostasis in peripheral tissues. Herein we describe an in vitro TregP cell differentiation assay that models the second, cytokine dependent, step of thymic Treg cell development. It can be utilized with relative ease to determine if a population of thymocytes represents a potential progenitor population for Treg cells as well as test how different cytokines or chemical inhibitors modulate the differentiation of known TregP cell populations into mature Treg cells.
Keywords: Thymus (胸腺)Background
Regulatory T cells (Treg) cells are a population of T cells that can suppress immune responses and are required to maintain immune tolerance and tissue homeostasis. While two broad classes of Treg cells have been described, thymic Treg cells (tTreg) and peripheral Treg cells (pTreg), the majority of Treg cells are generated during thymic selection (Asano et al., 1996). Early experiments describing autoimmune manifestations in thymectomized mice, which can be rescued by Treg cell transfer, confirm the importance of the thymus in generating Treg cells capable of maintaining immune homeostasis (Asano et al., 1996). The development of Treg cells in the thymus is a two-step process (Burchill et al., 2008; Lio and Hsieh, 2008). The first step is TCR mediated and gives rise to CD25+Foxp3- or CD25-Foxp3lo TregP cells. The second step is mediated by contact of these progenitor populations with intrathymic cytokines leading to co-expression of CD25 and Foxp3 and generation of mature tTreg cells.
The in vitro TregP conversion assay models the second, cytokine dependent, step in tTreg cell development. This assay builds on protocols initially described by work from Chyi Hsieh’s lab and modified by our own lab (Burchill et al., 2008; Lio and Hsieh, 2008). The technique described below provides a simple method to determine if an isolated thymic population represents a TregP, characterized by independence from TCR stimulation and upregulation of tTreg markers in response to cytokine. This assay has been performed with varied stimulation conditions previously, including stimulation with high concentrations of IL-2 (200 U/ml) (Tai et al., 2013) as well as IL-2 + IL-7 (Lio and Hsieh, 2008). The protocol we describe converts bona-fide TregP to mature Treg cells robustly and reproducibly with small amounts of IL-2 (Mahmud et al., 2014; Owen et al., 2019). As such, investigators can narrow the application of IL-2 to concentrations that are more physiologically relevant. This assay has also been able to detect conversion of TregP to mature Treg cells with other cytokines like IL-7, IL-15 and IL-4, as well as combination of factors such as IL-2 with TNFRSF agonists (Mahmud et al., 2014). Thus, the in vitro TregP conversion assay can be used to query various important stimulatory, or inhibitory, signals that may be encountered in vivo by developing TregP.
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版权信息
© 2019 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Owen, D. L. and Farrar, M. A. (2019). In vitro Differentiation of Thymic Treg Cell Progenitors to Mature Thymic Treg Cells. Bio-protocol 9(16): e3335. DOI: 10.21769/BioProtoc.3335.
分类
免疫学 > 免疫细胞分化 > T 细胞
细胞生物学 > 细胞分离和培养 > 细胞分化
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