The vast majority of CLA+ T cells are resident in normal skin.
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 approximately 1 x 10(6) T cells/cm(2) normal skin and an estimated 2 x 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.
Department of Dermatology, Brigham and Women's Hospital and Harvard Skin Disease Research Center, Boston, MA 02115, USA.
Rachael A
RA
Clark
Benjamin
B
Chong
Nina
N
Mirchandani
Nooshin K
NK
Brinster
Kei-Ichi
K
Yamanaka
Rebecca K
RK
Dowgiert
Thomas S
TS
Kupper
D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; D002465:Cell Movement; D002469:Cell Separation / Q000379:methods; D002478:Cells, Cultured; D019040:E-Selectin / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007156:Immunologic Memory; D008562:Membrane Glycoproteins / Q000378:metabolism*; D010641:Phenotype; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; C063419:CTAGE1 protein, human; D019040:E-Selectin; D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell