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Human Epidermal Langerhans Cells Maintain Immune Homeostasis in Skin by Activating Skin Resident Regulatory T Cells

Department of Dermatology/Harvard Skin Disease Research Center, Brigham and Women's Hospital, Boston, MA 02115, USA.
Immunity (Impact Factor: 21.56). 05/2012; 36(5):873-84. DOI: 10.1016/j.immuni.2012.03.018
Source: PubMed

ABSTRACT

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.

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Available from: Ahmed Gehad, Jan 05, 2016
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    • "In the skin, there are skin resident memory T cells with general marker (CLA + ,CD45O + ,CCR4 + ) 20 times more than in blood[13,14], resident memory (CD4 + CD25 + FOXP3 + CD127 -) regulatory T cells constitute 5% of these cells[15]. They are antigen specific and expanded by Langerhans dendritic cells which occur side by side with skin resident CD45O + effector memory cells[13]. Beside skin resident memory T cells, skin dendritic cells specially langerhans cells present antigen to naïve T cells in draining lymph nodes. Activated T cells resulted from antigen presentation got either effector resident T cell markers (CCR4 + , CLA + ) or of central memory T cell markers (CCR7, L-selectin )[11]figure(1). "

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    • "Along with this collagen, elastin and reticular fibers are also found in this layer, and fibroblast is found to be the main cellular component that constantly secretes collagen and proteoglycans. Other types of cells found in skin are melanocyte that is responsible for pigmentation and protection against UV radiation, and Langerhans cells that act as the first line of defense against invading microbes[26].8,192 of 17 beings consisting of three different layers, with each of these layers playing significantly critical roles, as a unit act as a barrier, thermo-regulator, and cushion to internal organs from outer environmental conditions18192021. The epidermal layer is avascular, consisting of 95% keratinocytes, and covers the dermal layer (Figure 1) that is permeated by a complex nervous and vascular network. "

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    • "In the skin, there are skin resident memory T cells with general marker (CLA + ,CD45O + ,CCR4 + ) 20 times more than in blood[13,14], resident memory (CD4 + CD25 + FOXP3 + CD127 -) regulatory T cells constitute 5% of these cells[15]. They are antigen specific and expanded by Langerhans dendritic cells which occur side by side with skin resident CD45O + effector memory cells[13]. Beside skin resident memory T cells, skin dendritic cells specially langerhans cells present antigen to naïve T cells in draining lymph nodes. Activated T cells resulted from antigen presentation got either effector resident T cell markers (CCR4 + , CLA + ) or of central memory T cell markers (CCR7, L-selectin )[11]figure(1). "
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