Perivascular leukocyte cluster: an essential structure for efficient effector T cell activation in the skin (IRC5P.467)

Abstract

Abstract It remains largely unclear how antigen-presenting cells encounter effector/memory T cells efficiently in the periphery. Here we used a murine contact hypersensitivity model to analyze antigen presentation in the skin. By antigen challenge, dendritic cells (DCs) formed clusters with effector T cells in dermal perivascular areas to promote in situ proliferation and activation of effector T cells in antigen- and integrin LFA-1-dependent manners. Intriguingly, DCs were attracted toward perivascular macrophages and DC clustering was abrogated by macrophage-depletion. IL-1α treatment induced CXCL2 production from dermal macrophages, and DC clustering was suppressed with blockade of either IL-1R or CXCR2. These findings suggest that dermal leukocyte cluster is an essential structure for elicitation of the acquired cutaneous immunity.