Naive T-cell cycling and thymic function under HAART. Naive T-cell cycling was quantified through Ki-67 expression on CD45RA⁺, CD27⁺ cells in the CD4⁺ (A) and CD8⁺ (B) compartments. Immunologic responders (IRs; n = 13) as well as poor responders (PIRs, n = 7) are compared with healthy control subjects (Ctl) and untreated HIV-infected persons (P). The subgroups of patients analyzed are representative of their respective patient population described in Table 1 with respect to age, CD4 counts, and viral load. Statistical differences between groups are shown on top (*P < .05; **P < .01). (C) Thymic function was estimated through the calculation of the sj/βTREC ratio in the 4 groups of individuals (PIR, n = 11; IR, n = 12). Horizontal lines represent maximal values, third quartiles, medians, first quartiles, and minimal values, from top to bottom. The IR patient with an sjTREC frequency of 17 sjTREC/10⁵ cells did not show any detectable DJβTREC; thus, his sj/βTREC ratio was impossible to calculate. The sj/βTREC ratio (D), sjTREC (E), and DJβTREC (F) frequencies are presented as a function of age for group PIR (closed symbols) and IR (open symbols). For one IR and one PIR patient, DJβTRECs were undetectable in triplicate experiments, the sj/βTREC ratio was thus impossible to calculate for these patients. The lines represent the linear regressions for the control group.