Effect of CD27-CD70 interaction on Foxp3 induction in CD4⁺CD25⁻ T-cell biopsy specimens of B-cell NHL. (A) Representative dot plots showing CD70 expression on CD19⁺ B cells in biopsy specimens from patients with lymphoma or biopsy specimens from patients with follicular hyperplasia or PBMCs from healthy individuals. Percentages indicate number of CD19⁺CD70⁺ cells as a percentage of all unsorted mononuclear cells. (B) Summarization of frequency of CD19⁺CD70⁺ cells in biopsy specimens of patients with NHL (n = 11). The horizontal bar represents the median Foxp3 expression level. (C) CD70⁺ (CD70⁺ LB) and CD70⁻ (CD70⁻ LB) lymphoma B cells were isolated by flow sorting and cocultured with intratumoral CD4⁺CD25⁻ T cells in plates coated with (OKT3) or without (R) OKT3 for 3 days. Foxp3 expression was determined by intracellular staining. (D) Summarization of Foxp3 induction in CD4⁺CD25⁻ T cells cocultured with lymphoma B cells (LB) treated with anti-CD70 Ab alone (LB/anti-CD70), or combination with anti-CD80 and CD86 Abs (LB/anti-CD70 + CD80CD86) in plates precoated with OKT3 for 3 days. Foxp3 expression was determined by intracellular staining. Foxp3 induction is indicated by fold change to group without stimulation (mean ± SE). *P < .05 compared with group with LB alone; **P < .01 compared with group with LB alone.