CD4(+) and CD8(+) T lymphocyte regeneration after anti-retroviral therapy in HIV-1-infected children and adult patients

Previous studies have shown a slow recovery of naive CD4(+) T cell counts a fter anti-retroviral therapy in HIV-1-infected adults, which is in accordan ce with thymus atrophy after puberty. Here we investigate whether or not di fferent patterns of naive CD4(+) and CD8(+) T cell repopulation are present in adult and child patients undergoing anti-retroviral treatment. Thus, 25 adults under highly active anti-retroviral therapy and 10 children under c ombined anti-retroviral therapy were retrospectively analysed for T cell su bpopulations at baseline (T0) and around week 12 (T1) and week 24 (T2) of a nti-retroviral treatment. Mean serum HIV-1 RNA levels dropped in both group s. Recovery of T cells in adults was characterized by a heterogeneous respo nse between patients, with only 44% of them increasing their naive CD4(+) a nd CD8(+) T cell counts at T1, and changes in mean total CD4(+) T cells wer e mainly shaped by memory cells. Otherwise, children were characterized by an early increase in naive T cells. Thus, at T1, all children analysed had a strong rise in CD4(+) (from 389 +/- 116 to 569 +/- 121 cells/mu l; P < 0. 01), and nine out of 10 also in naive CD8(+) T cells (from 244 +/- 58 to 47 3 +/- 85 cells/mu l; P < 0.05). However, no significant correlation between age and naive repopulation was observed (P = 0.22) in children. Thus, chil dren had the earlier and greater increases in naive T cell subsets than adu lts, probably due to a more active thymus, with the potential for immune re constitution when HIV-1 replication is controlled.