Antigen expression on CD4⁺CD25⁺ T cells from biopsy specimens of patients with B-cell NHL. (A) Dot plots showing CD25 expression on CD4⁺ T cells in freshly isolated cell suspensions from the tissue types indicated. (B) Frequency (mean ± SD) of CD4⁺CD25⁺ among normal peripheral blood mononuclear cells (PBMCs) (n = 6), cells from inflammatory tonsils (n = 6), and benign/reactive LNs (n = 6). ^*P < .001, compared with benign/reactive LNs. (C) The phenotypic analysis of CD4⁺CD25⁺ T cells in B-cell NHL. The line was drawn based on the isotype control. The set of histograms is a representative of 6 samples. (D) Dot plots showing intracellular staining of Foxp3 or CTLA-4 as well as their corresponding isotype control in CD3⁺ CD4⁺CD25^+/- T cells. Patient sample nos. 1 to 4, nos. 6 to 11, and no. 24 were used in these experiments.