Administration of high-dose IL-2 alters lymphocyte counts. (A) Patients received 3 daily doses of high-dose IL-2 as tolerated (total of 7-11 doses per patient). Patients were leukapheresed prior to the start of treatment on day 0 (PRE), during the peak of lymphocytosis or rebound (REB), and about 2 to 3 weeks after therapy (POST), as indicated by the arrows. Absolute lymphocyte counts (ALCs) were measured daily. The percent of CD4⁺ (B) and CD8⁺ (C) T cells per CD3⁺ T-cell population was quantified for 8 patients by staining PBMCs with anti-CD4 and anti-CD3 antibodies. The dot plots were gated on live (propidium idodide negative, PI^-) CD3⁺ T cells. For CD8 T cells, CD3⁺CD4^- T cells were considered as CD8 T cells in some experiments. Each symbol represents one patient. Leukaphereses samples for POST were available only for 5 patients. P values were determined using paired t test and adjusted for multiple comparisons.