CD4 and AIDS: Although recent studies have shown independent associations between lower CD4+/CD8+ T-cell ratio, subclinical markers of age related diseases [24], risk of non-AIDS morbidity or mortality [25] and persistent immune activation despite ART [15], a large Canadian cohort study failed to find an association between normalization of the CD4+/CD8+ ratio (defined as a ratio ≥1.2) and the probability of AIDS defining illness or death [14].