NHL tumor cells induce CD25⁺ Treg cells. Panels show induction of CD25⁺FoxP3⁺ Treg cells from CFSE-labeled CD25⁻ PBMC fractions with different ratios of tumor cells or CD304⁺ cell– and CD25⁺ cell–depleted involved tissue cell fractions. (A) The left-hand panel summarizes the percentages of CD25⁺FoxP3 Treg cells after 5 days of incubation with different ratios of tumor cells or CD304⁺- and CD25⁺-depleted involved tissue fractions (n = 6). (B) The plots shown on the right give examples of flow cytometric plots used to generate the graphs and typical examples of CFSE staining on cells gated on CD25 and FoxP3.