Transcriptional Analysis of T Cells Resident in Human Skin

Human skin contains various populations of memory T cells in permanent residence and in transit. Arguably, the best characterized of the skin subsets are the CD8(+) permanently resident memory T cells (T(RM)) expressing the integrin subunit, CD103. In order to investigate the remaining skin T cells, we isolated skin-tropic (CLA(+)) helper T cells, regulatory T cells, and CD8(+) CD103(-) T cells from skin and blood for RNA microarray analysis to compare the transcriptional profiles of these groups. We found that despite their common tropism, the T cells isolated from skin were transcriptionally distinct from blood-derived CLA(+) T cells. A shared pool of genes contributed to the skin/blood discrepancy, with substantial overlap in differentially expressed genes between each T cell subset. Gene set enrichment analysis further showed that the differential gene profiles of each human skin T cell subset were significantly enriched for previously identified T(RM) core signature genes. Our results support the hypothesis that human skin may contain additional T(RM) or T(RM)-like populations.