Study outline and NKT cell phenotyping. (A) Thirty-two subjects with primary HIV-1 infection were enrolled in 3 different treatment groups. Twenty-one subjects started ART; 10 went on additional IL-2 treatment once their HIV-1 RNA level was below 500 copies/mL. Eleven subjects remained untreated. Whole-blood samples were collected at month 0 (prior to ART treatment), month 1 (before initiation of IL-2), and at months 6 and 12 (after completion of 2 and 5 cycles of IL-2 treatment, respectively). Blood samples were drawn in all patient groups at the stated time points. (B) NKT cells identified by coexpression of Vα24 and Vβ11 express CD161 and CCR5 on both the CD4⁺ and CD4^– subset.