CCR4 and B-cell chronic lymphocytic leukemia: Therefore, we further characterized CD26+ and their CD26neg counterparts in CLL patients, which showed CD26high cells were enriched with Tc17 (CCR4+CCR6+) and Tc1/Tc17 (CCR6+CXCR3+) CD8+ T cell phenotype but Tc2 (CCR4+CCR6−) CD8+ T cells were more abundant in CD26neg and CD26low T cell subsets (Additional file 1: Fig. S3p–u).