A skin-selective homing mechanism for human immune surveillance T cells

J Exp Med. 2004 May 3;199(9):1265-75. doi: 10.1084/jem.20032177.

Abstract

Effective immune surveillance is essential for maintaining protection and homeostasis of peripheral tissues. However, mechanisms controlling memory T cell migration to peripheral tissues such as the skin are poorly understood. Here, we show that the majority of human T cells in healthy skin express the chemokine receptor CCR8 and respond to its selective ligand I-309/CCL1. These CCR8(+) T cells are absent in small intestine and colon tissue, and are extremely rare in peripheral blood, suggesting healthy skin as their physiological target site. Cutaneous CCR8(+) T cells are preactivated and secrete proinflammatory cytokines such as tumor necrosis factor-alpha and interferon-gamma, but lack markers of cytolytic T cells. Secretion of interleukin (IL)-4, IL-10, and transforming growth factor-beta was low to undetectable, arguing against a strict association of CCR8 expression with either T helper cell 2 or regulatory T cell subsets. Potential precursors of skin surveillance T cells in peripheral blood may correspond to the minor subset of CCR8(+)CD25(-) T cells. Importantly, CCL1 is constitutively expressed at strategic cutaneous locations, including dermal microvessels and epidermal antigen-presenting cells. For the first time, these findings define a chemokine system for homeostatic T cell traffic in normal human skin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD / blood
  • Antigens, CD / immunology
  • Cells, Cultured
  • Cytokines / biosynthesis
  • Cytokines / immunology
  • Humans
  • Immunologic Memory / immunology
  • Immunophenotyping
  • Receptors, CCR8
  • Receptors, Chemokine / immunology*
  • Receptors, Lymphocyte Homing / immunology*
  • Skin / immunology*
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology*

Substances

  • Antigens, CD
  • CCR8 protein, human
  • Cytokines
  • Receptors, CCR8
  • Receptors, Chemokine
  • Receptors, Lymphocyte Homing