Fig. 6.

Effect of chemotherapy on regulatory T cell frequency. Effect of different drug treatments (x-axis) on CD4⁺ forkhead box P3 (FoxP3)⁺ frequency in chronic lymphocytic leukaemia (CLL) patients (a). Solid line represents median. P < 0·05 using Friedman's test (paired non-parametric) as indicated by bars on top of graph. CD4⁺FoxP3⁺ T cells were enumerated prior to, during and post-fludarabine treatment (x-axis in weeks) in two patients (b). Number of total CD4⁺ (solid triangle) and CD4⁺FoxP3⁺ T cells (open triangles) per µl of blood (primary y-axis) and % CD4⁺FoxP3⁺ T cells (closed circles) (secondary y-axis). (c) Half-life in decay of total number of CD4⁺ (squares) and CD4⁺FoxP3⁺ (triangles) T cells following fludarabine treatment (≥ 30 weeks from start of treatment).