T cell distribution in human skin. (A) Epidermal- and dermal-resident αβ⁺ and Vδ1⁺ T cells express high levels of CLA. Representative cytometry plots show gated populations from four-color immunofluorescence. Epidermal and dermal cells were stained with anti-CD3, CLA, αβ, and Vδ1 antibodies and were compared with healthy blood. Live lymphocytes were gated according to forward and side scatter. The numbers denote the percentages of gated cells from the live cell gate shown. (B) There is a significant difference in CLA expression between blood and epidermal T cells. There is no difference in terms of CLA expression between epidermal and dermal T cells. Histograms show the percentage of CD3⁺, CLA⁺, αβ⁺, and Vδ1⁺ cells in the blood, epidermis, and dermis of healthy donors. Results represent means of data ± SEM of four normal skin samples (epidermis and dermis) and five healthy blood samples. (C) The Vδ1/αβ T cell ratio is significantly different between the blood and epidermis as well as between the epidermis and dermis. Plots show the ratio of αβ⁺ to Vδ1⁺ T cells in the blood, epidermis, and dermis of individual healthy donors. Ratios were compared using a one-tailed unpaired Student's t test. Horizontal bars represent means of the values from the different patients.