Lymphocyte subsets in human immunodeficiency virus type 1-infected and uninfected children in Nairobi

Background. Reference lymphocyte subset values for African children are lac king. This study documents these values as well as their alterations associ ated with perinatal and postnatal HIV-1 transmission and with protection fr om HIV-1 infection. Methods. Lymphocyte subsets were determined for HIV-1-seronegative nonpregn ant women and their children (controls) and for uninfected, perinatally inf ected and postnatally infected children born to HIV-1-seropositive mothers in Nairobi, Kenya. The mean, median and 5th and 95th percentile values for CD4(+) and CD8(+) lymphocyte counts and percentages were determined and com pared at the age ranges birth to 3 months, 4 months to 1 year, yearly from 1 to 5 years and from 6 to 10 years of age, Results. Among control children counts differed from published values of ot her populations. In all age ranges, whereas the absolute values were signif icantly higher than adult values, the percentages were significantly lower, Children perinatally infected with HIV-1 had clearly distinguishable diffe rences in lymphocyte subset percentages by 3 months of age, when the median CD4(+) percentage was 27.9% (5th to 95th percentile, 25.7 to 30.1%) for in fected vs. 35.9% (33.3 to 38.7%) for uninfected and 39.9% (37.8 to 42.2%) f or control children, P < 0.001; whereas the median CD8(+) percentage was 37 .0% (33.1 to 41.0%) for infected vs. 27.5% (24.2 to 30.8%) for uninfected a nd 27.5% (24.2 to 30.8%) for control children, P = 0.001. Differences betwe en uninfected and control children disappeared after 1 year of age. Conclusions. Normal lymphocyte subset values among African children differ from those in other populations. Significant differences are detectable by 3 months of age in CD4(+) and CD8(+) lymphocyte percentages among perinatal ly infected infants, which may be useful as an adjunct in diagnosis. Transi ent differences observed among HIV-1-exposed but uninfected infants could r eflect a successful immune response to HIV-1 challenge.