Figure 1.

Healthy Human Skin Contains a Population of Clonally Enriched CD49a⁺ Trm Cells in Epidermis

(A–C) Phenotypic analysis of live CD3⁺TCRγδ⁻ T cells from blood, dermis, and epidermis from healthy donors (n = 20). (A) Representative FACS plots of CD103, CD69, and CD49a expression in epidermal CD4 or CD8 T cells. (B and C) Frequencies of CD103⁺CD69⁺ (B) and CD103⁺CD69⁺CD49a⁺ (C) in CD4⁺ or CD8⁺ T cells. Each point represents data from an individual donor. Median depicted. Two-tailed Wilcoxon tests, ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.

(D) Confocal image of cryopreserved healthy skin depicting CD8 (red), Keratin5/6 (blue), and collagen IV (white). Scale bar, 100 μm.

(E) Confocal images of epidermal CD8⁺CD49⁻ (upper panel) and CD8⁺CD49⁺ (lower panel) cells relative to the collagen IV-rich basement membrane. CD8 (red), CD49a (green) DAPI (blue), collagen IV (white) are depicted. Scale bars, 10 μm. Images are representative of ten healthy donors.

(F–J) Analysis of TCRβ CDR3 region in sorted CD8⁺ T cells from blood, dermis, and epidermis of healthy donors (n = 5). (F) Pie charts show the frequency of TCR Vβ families in T cell subsets from three donors. The top three Vβ families in epidermal CD8⁺CD103⁺CD49a⁺ are marked by color-coded asterisks. (G) The cumulative frequency of reads among top 20 clonotypes from epidermal CD8⁺CD103⁺CD49a^– (left) and CD8⁺CD103⁺CD49a⁺ (right) Trm cells. (H) Proportion of shared clonotypes (left) and cumulative frequency of shared reads (right) between CD8⁺CD103⁺CD49a^– and CD8⁺CD103⁺CD49a⁺ Trm cells. (I) Log scatterplot from donor 1–3 showing proportion of reads for each unique clonotype in CD8⁺CD103⁺CD49a^– and CD8⁺CD103⁺CD49a⁺ Trm cells. Major shared clones are highlighted with red circles. (J) Total frequency of productive reads of the top ten clonotypes of CD8⁺CD103⁺CD49a^– (left) and CD8⁺CD103⁺CD49a⁺ (right) Trm cells in the total reads of CD8⁺ T cell subsets in blood, dermis and epidermis. Mean ± SD is depicted. See also Figure S1.