Long-term expansion of CD4⁺ T cells is reduced in recipients of CCR6-deficient donor cells. CD4⁺ T-cell number after GvHD induction in CB17/SCID recipients of WT (▪), CCR6-deficient (▦), or BALB/c (□) CD4⁺ naive T cells is shown for recipient spleen (A) and blood (B) at different time points. Values represent the mean ± SD (n = 2-4 mice/group/time-point). Similar results were observed in 2 independent experiments. (C) Real-time quantitative RT-PCR determination of cytokine transcript levels in the spleen of recipient mice measured over time. □ indicates IFN-γ; ▦, IL-10; ▪, IL-4; and ▨ IL-12).