Effect of lymphoma B cells on activation-induced Foxp3 expression in CD4⁺CD25⁻ T-cell biopsy specimens of B-cell NHL. (A) Purified CD4⁺CD25⁻CD127⁺ T cells were cultured in OKT3-coated plates (OKT3) or with the addition of anti-CD28 Ab (OKT3/aCD28) or CD19⁺ lymphoma cells (OKT3 + LB) for 3 days. Unstimulated cells (Resting) were used as the baseline for calculating Foxp3 induction. Foxp3 expression was examined by intracellular staining. Numbers indicate CD4⁺Foxp3⁺ cells as a percentage of all cells. (B) Summarization of Foxp3 induction in CD4⁺CD25⁻ T cells upon activation with OKT3 alone (OKT3; n = 15) or plus anti-CD28 (+ aCD28; n = 6) or in the presence of lymphoma B cells (+ LB; n = 15). Foxp3 induction is indicated by fold change to group without stimulation (Resting). The horizontal bars indicate median.