Immuni：美阐明朗格汉斯细胞维持免疫自稳的机制

日前，美研究人员在线发表了题为《Human Epidermal Langerhans Cells Maintain Immune Homeostasis in Skin by Activating Skin Resident Regulatory T Cells》研究论文，阐明了朗格汉斯细胞是如何维持皮肤组织的免疫自稳。该研究论文发表在国际期刊Immunity上。

正常成年人的皮肤中常驻着100-200亿个记忆T细胞，其中包括各种辅助性T细胞、细胞毒素T细胞和调节性T细胞，它们随时准备着与抗原发生反应。

当未受到外界抗原的刺激时，表皮的朗格汉斯细胞特异性地选择并激活皮肤中的调节性T细胞；当受到外界抗原的刺激时，表皮的朗格汉斯细胞限制调节性T细胞的激活，却特异性地激活并诱导记忆T细胞的增殖。

最终，朗格汉斯细胞在皮肤中的作用得到了阐明，即在未受外界抗原的刺激时保持机体免疫耐受；受到外界抗原的刺激时激活记忆T细胞发挥防护作用。

doi.org/10.1016/j.immuni.2012.03.018
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Human Epidermal Langerhans Cells Maintain Immune Homeostasis in Skin by Activating Skin Resident Regulatory T Cells

Julien Seneschal1, 2, Rachael A. Clark1, Ahmed Gehad1, Clare M. Baecher-Allan1, Thomas S. Kupper1,

1 Department of Dermatology/Harvard Skin Disease Research Center, Brigham and Women's Hospital, Boston, MA 02115, USA

2 Department of Dermatology and Pediatric Dermatology/ University of Bordeaux, INSERM U1035 and CIRID UMR 5164, Bordeaux, France

Summary

Recent studies have demonstrated that the skin of a normal adult human contains 10–20 billion resident memory T cells, including various helper, cytotoxic, and regulatory T cell subsets, that are poised to respond to environmental antigens. Using only autologous human tissues, we report that both in vitro and in vivo, resting epidermal Langerhan cells (LCs) selectively and specifically induced the activation and proliferation of skin resident regulatory T (Treg) cells, a minor subset of skin resident memory T cells. In the presence of foreign pathogen, however, the same LCs activated and induced proliferation of effector memory T (Tem) cells and limited Treg cells' activation. These underappreciated properties of LCs, namely maintenance of tolerance in normal skin, and activation of protective skin resident memory T cells upon infectious challenge, help clarify the role of LCs in skin.