Expansion of the CD4⁺ T-cell pool while TREC numbers remained stable in healthy children. (A) In healthy children, total body CD4⁺ T-cell numbers (○) increased with age, but total body TREC numbers (•) did not change over time. (B) HIV-1 infection was associated with low and stable numbers of total body CD4⁺ T cells (○) and TRECs (•).