The vast majority of CLA+ T cells are resident in normal skin

RA Clark, B Chong, N Mirchandani… - The Journal of …, 2006 - journals.aai.org
RA Clark, B Chong, N Mirchandani, NK Brinster, K Yamanaka, RK Dowgiert, TS Kupper
The Journal of Immunology, 2006journals.aai.org
There are T cells within normal, noninflamed skin that most likely conduct
immunosurveillance and are implicated in the development of psoriasis. We isolated T cells
from normal human skin using both established and novel methods. Skin resident T cells
expressed high levels of CLA, CCR4, and CCR6, and a subset expressed CCR8 and
CXCR6. Skin T cells had a remarkably diverse TCR repertoire and were mostly Th1 memory
effector cells with smaller subsets of central memory, Th2, and functional T regulatory cells …
Abstract
There are T cells within normal, noninflamed skin that most likely conduct immunosurveillance and are implicated in the development of psoriasis. We isolated T cells from normal human skin using both established and novel methods. Skin resident T cells expressed high levels of CLA, CCR4, and CCR6, and a subset expressed CCR8 and CXCR6. Skin T cells had a remarkably diverse TCR repertoire and were mostly Th1 memory effector cells with smaller subsets of central memory, Th2, and functional T regulatory cells. We isolated a surprising number of nonexpanded T cells from normal skin. To validate this finding, we counted T cells in sections of normal skin and determined that there are∼ 1× 10 6 T cells/cm 2 normal skin and an estimated 2× 10 10 T cells in the entire skin surface, nearly twice the number of T cells in the circulation. Moreover, we estimate that 98% of CLA+ effector memory T cells are resident in normal skin under resting conditions. These findings demonstrate that there is a large pool of memory T cells in normal skin that can initiate and perpetuate immune reactions in the absence of T cell recruitment from the blood.
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