Regulation of CCR8 expression by epidermal keratinocytes. (A-B) Peripheral blood naive T cells were left unstimulated (keratinocytes alone) or stimulated with αCD3/CD28 beads for 6 days alone (media) or in coculture with epidermal keratinocytes (kerat), dermal fibroblasts (fibro), mesothelial cells (meso), or small intestinal epithelial cells (intest epi). (A) Representative flow cytometric dot plots showing CCR8 expression on gated CD3⁺ T cells after 6 days. (B) Combined expression data for CCR8 and CXCR3 by CD4⁺ (left panels) and CD8⁺ T cells (right panels) from all cocultures are plotted as mean ± SD from 2-4 independent experiments. **P < .01, comparing cocultures versus beads alone. ***P < .001, comparing cocultures versus beads alone. (C) Naive T cells cocultured with primary keratinocytes for 6 days were harvested and either left untreated or treated with 100nM CCL1 for 30 minutes at 37°C before staining for CCR8 expression. Representative dot plots of CCR8 versus CXCR3 expression on gated CD3⁺ T cells. (D) Transwell migration of CD4⁺ T cells toward 0, 1, 10, or 100nM CCL1 after activation in the presence of keratinocytes for 6 days. The numbers of migrating cells or calculated as a percentage of input cells and plotted as mean ± SD. Results shown are representative of 3 independent experiments with similar results.