Fig. 5.

Chronic lymphocytic leukaemia (CLL) tumour cells enhance expression of forkhead box P3 (FoxP3) in CD4⁺CD25^- T cells (a) Purified CD4⁺CD25^-CD127⁺ T cells were sorted by flow cytometry and shown to be negative for FoxP3 expression. (b) Cells were then cultured alone or with the addition of either B blasts, directly isolated CLL cells or preactivated CLL cells. Incubations were performed at a 1:10 ratio for 5 days. Representative flow cytometric plots are shown for each culture condition. The percentage in the top right quadrant indicates the number of CD4⁺ T cells which stain positively for FoxP3. (c) Summary of relative FoxP3 induction in CD4⁺CD25^- T cells following co-culture with B blasts (n = 5), directly isolated ex vivo CLL (n = 12) or preactivated CLL (n = 12). T cells alone were used as baseline for calculating FoxP3 induction (y-axis). Column bars indicate mean ± standard error (s.e.). P < 0·05 using Kruskal–Wallis test as indicated by bars on top of graph.