To further substantiate the relevance of the CCR6-CCL20 pathway in guiding migration of CD161-expressing T cells to GVHD-prone organs, we next determined CCL20 expression in situ in skin biopsies obtained from allo-SCT recipients who developed acute or chronic GVHD (Figure 7A, Figure S4). This evidence concerns the gene CCR6 and chronic graft versus host disease.