Keratinocyte-induced CCR8 expression is mediated by soluble factors. (A) Naive T cells were stimulated with αCD3/CD28 beads for 6 days either in direct contact with a monolayer of epidermal keratinocytes (together) or separated from the keratinocyte monolayer by a 0.4-μm transwell insert (separate). After 6 days, CCR8 expression was analyzed by flow cytometry. Data are plotted as the mean ± SEM for gated CD3⁺, CD4⁺, and CD8⁺ T cells from 2 independent experiments. (B-C) Purified allogeneic naive T cells were cocultured for 9 days with MACS-enriched epidermal LCs, dermal CD1a⁺ DCs, dermal CD14⁺ DCs, or MDDCs at a ratio of 10:1 in the absence or presence of KCM. (B) The percentage of T cells expressing CCR8 after 9 days in coculture with epidermal LCs or MDDCs in media alone or media supplemented with 50% KCM are plotted as mean ± SD (n = 4-10). *P < .05. (C) Percentage of CD3⁺ T cells expressing CCR8, CLA, CCR4, or CXCR3 after coculture with LCs, dermal CD1a⁺ DCs, or dermal CD14⁺ DC in the absence (media) or presence of KCM are plotted as mean ± SEM from 2 or 3 independent experiments. ***P < .001