IL-2 administration leads to increases in naive and recall memory but not effector memory CD4⁺ T cells. The median counts of CD4⁺ (A-B) and CD8⁺ (C-D) T-cell subsets from the IL-2 and control groups from cohort 2 are shown at month 0 (baseline) and month 12. In IL-2 recipients, significant increases in the naive and recall memory CD4 subsets (P < .001) were observed compared to month 0 values (paired analysis) and when they were compared to controls at month 12. No statistically significant changes were noted in the control group at month 12 compared to month 0, except for a significant decrease in recall memory CD4⁺ T cells (P = .01).