Most Foxp3⁺ T cells during early lymphocyte recovery after induction chemotherapy are proliferating activated regulatory T cells. On the basis of a previous study by Miyara et al with the use of relative expression of Foxp3 and CD45RA,³³  flow cytometric analysis was used to partition Foxp3⁺ T cells into 3 subsets. Data from a representative healthy control and patient are shown graphically, whereas the subset analyses for all controls and patients tested are shown in the table. The population of CD45RA⁻Foxp3^+lo effector (nonregulatory) T cells in patients during early lymphocyte recovery after TST is similar to that seen in healthy controls (P = .866). Unlike healthy controls, patients do not have an appreciable population of naive regulatory T cells. Conversely, patients have a significantly expanded population of activated regulatory T cells (P < .001), which are proliferating much more rapidly than activated regulatory T cells found in controls (P = .029). APC indicates allophycocyanin.