Background. Interleukin (IL)-2 increases CD4 T cell counts when combined with antiretroviral therapy (ART). Whether IL-2 alone can increase CD4 cell counts is unknown.Methods. A total of 130 adults who had a CD4 cell count of 300-500 cells/mu L (and, thus, were not eligible to receive ART) were randomized to receive either intermittent IL-2 therapy or no treatment. The primary end point was a drop in CD4 cell count to <300 cells/mu L, initiation of ART, the occurrence of an AIDS-defining event, or death.Results. Through week 96, 35% of the patients in the IL-2 arm and 59% in the control arm reached the primary end point (P = .008). Median changes from baseline in the IL-2 and control arms were +51 and -64 cells/mu L, respectively, for CD4 cell count (P < .001) and were +0.02 and +0.04 log(10) copies/mL, respectively, for plasma viral load (P = .93). Among patients with a baseline viral load <4.5 log(10) copies/mL, 64% in the IL-2 arm and 10% in the control arm did not reach the primary end point through week 150 (P < .001), and the time to ART initiation was deferred by 92 weeks in the IL-2 arm. The incidences of an AIDS-defining event, death, and grade 3 or 4 adverse events were similar between study arms.Conclusion. IL-2 increased CD4 cell counts without affecting HIV replication and allowed the initiation of ART to be deferred.
