Antibody-producing donor B cells associate with augmented Th17 infiltration and increased expression of CCL20 in the skin. HCT was carried out with BALB/c recipients as described in Figure 1. (A-B) Percentage of IL-17⁺ cells among donor CD4⁺ T cells at days 40 (A) and 60 (B) after HCT. Donor CD5.1⁺CD4⁺ T cells from spleen, PLNs, and skin were analyzed with intracellular staining of IL-17. Cells were gated on CD5.1⁺TCRβ⁺ and displayed as IL-17 vs CD4. Representative patterns and means ± SE of the percentage of donor IL17⁺CD4⁺ T cells in the spleen, PLNs, and skin are shown. N = 4-6 from at least 2 replicate experiments. (C) Percentage of CCR6⁺ donor CD4⁺T cells and CCR6⁺IL17⁺ double-positive donor CD4⁺ T cells at day 40 after HCT. Representative patterns and means ± SE of the percentage of donor CCR6⁺CD4⁺ T cells or CCR6⁺IL17⁺ double-positive CD4⁺ T cells in PLNs are shown. N = 4 from at least 2 replicate experiments for each group. (D) Means ± SE of CCL20 chemokine expression in skin at 40 and 60 days after HCT. Relative gene expression levels were normalized within each sample to the housekeeping gene GAPDH. N = 3 from 3 replicate experiments with triplicates (**P < .01, ***P < .001). (E) Representative staining pattern of donor IL-17⁺CD4⁺ T cells in skin at day 50 after HCT. N = 3.