Effect of IL-2 on Tregs in vivo is transient. (A) Percent changes in frequencies of CD4⁺CD25⁺/CD3⁺ were calculated using phenotypic values obtained from samples collected during IL-2 treatment and samples collected at later time points, 4 to 10 months after IL-2 therapy (Table 1). Patients with solid tumors are represented with ; patients after allogeneic HSCT are represented with ▪. (B) FOXP3 expression was assessed in the same samples collected during IL-2 treatment and after completion of therapy (Table 1). Percent changes were calculated using values obtained with these 2 sets of samples.