Median (interquartile range) CD4+ naive-memory cell ratios by baseline CD4+ stratum and study week for patients who underwent comprehensive immunological assessments by advanced flow cytometry and HIV-negative control subjects (from AIDS Clinical Trials Group [ACTG] protocol A5113) [33]. The y-axis reflects the absolute count for both CD4+ naive and memory cells. CD4+ naive-memory cell ratios are shown above the bars at each time point, and the interquartile ranges are shown above, in parentheses. Results for HIV-negative control subjects from ACTG protocol A5113 are shown to the right of the week 144 bars, for comparison. After controlling for baseline HIV RNA level, the CD4+ naive-memory cell ratio for stratum 1 was significantly different from stratum 3 (weeks 0 and 24), stratum 4 (weeks 0, 24, 48, and 96), and stratum 5 (weeks 0, 24, and 48), and the stratum 2 CD4+ naive-memory ratio was significantly different from stratum 4 (weeks 24 and 96) and stratum 5 (weeks 0, 24, and 48).