[HTML][HTML] Skin CD4+ memory T cells exhibit combined cluster-mediated retention and equilibration with the circulation

N Collins, X Jiang, A Zaid, BL Macleod, J Li… - Nature …, 2016 - nature.com
Nature communications, 2016nature.com
Although memory T cells within barrier tissues can persist as permanent residents, at least
some exchange with blood. The extent to which this occurs is unclear. Here we show that
memory CD4+ T cells in mouse skin are in equilibrium with the circulation at steady state.
These cells are dispersed throughout the inter-follicular regions of the dermis and form
clusters with antigen presenting cells around hair follicles. After infection or administration of
a contact sensitizing agent, there is a sustained increase in skin CD4+ T-cell content, which …
Abstract
Although memory T cells within barrier tissues can persist as permanent residents, at least some exchange with blood. The extent to which this occurs is unclear. Here we show that memory CD4+ T cells in mouse skin are in equilibrium with the circulation at steady state. These cells are dispersed throughout the inter-follicular regions of the dermis and form clusters with antigen presenting cells around hair follicles. After infection or administration of a contact sensitizing agent, there is a sustained increase in skin CD4+ T-cell content, which is confined to the clusters, with a concomitant CCL5-dependent increase in CD4+ T-cell recruitment. Skin CCL5 is derived from CD11b+ cells and CD8+ T cells, with the elimination of the latter decreasing CD4+ T-cell numbers. These results reveal a complex pattern of tissue-retention and equilibration for CD4+ memory T cells in skin, which is altered by infection and inflammation history.
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