Lymphocyte Phenotyping in Infants: Maturation of Lymphocyte Subpopulations and the Effects of HIV Infection

Changes in the distribution of lymphocyte subpopulations in infants with perinatally acquired HIV infection are confounded by the rapid changes that are the result of normal maturation of the immune system. We describe the changes in seven lymphocyte phenotypes (CD3+ CD4+, CD3+ CD8+, CD8+ HLA- DR+, CD8+ CD38+, CD8+ CD57+, CD3-/ CD16+ 56+, and CD19+) over the first 2 years of life in 390 HIV-1 exposed but uninfected and 98 HIV-1-infected infants enrolled in the Women and Infants Transmission Study. The greatest changes in uninfected infants were declines in the CD3+ CD4+ lymphocytes and increases in CD8+ HLA- DR+ and CD19+ lymphocytes. All phenotypes were affected by HIV infection but the greatest changes were declines in the CD3+ CD4+ subset and increases in the CD3+ CD8+ and CD8+ HLA- DR+ subsets. Thus, this study provides reference data for the maturational changes in lymphocyte phenotypes in HIV-exposed but uninfected infants and describes the overall changes that occur with perinatally acquired HIV infection.