The interaction between CCL22 and CCR4 is involved in the migration of CD4⁺CD25⁺ T cells to tumor sites of B-cell NHL. (A) Dot plots showing the expression of CCR4 and CCR8 on CD4⁺ T cells from biopsy specimens of B-cell NHL (n = 6). (B) Histograms showing intracellular expression of CCL17 and CCL22 in CD20⁺ lymphoma B cells from biopsy specimens of B-cell NHL (n = 6). The shaded histogram represents the isotype control staining, and the open histogram represents the CCL17 or CCL22 staining. (C) The bar graph showing CD4⁺CD25⁺ T-cell migration in response to supernatant of lymphoma B cells (SP). CD4⁺CD25⁺ T cells were labeled with calcein AM, and the fluorescence intensity of migrated cells was measured by fluorescent plate reader. Results are the mean ± SD, n = 6, ^*P < .01, compared with media alone; #P < .05, compared with supernatant. Patient sample nos. 3, 10, 11, 16, 17, and 20 to 23 were used in these experiments.