T-lymphocyte subsets in West African children: Impact of age, sex, and season

Objective: There has been no reference material for T-lymphocyte subsets for normal children in developing countries. We therefore used T-lymphocyte subset determinations among children in three different studies in Guinea-Bissau to construct age-related reference material and to examine possible determinants of T-lymphocyte subset levels. Methods: A total of 803 healthy West African children younger than 6 years were included in the three community studies of T-lymphocyte subsets among twins and singletons, after measles infection and after measles immunization. We used the immunoalkaline phosphatase method to determine T-lymphocyte subsets. Results: We found differences by age, sex, and season, whereas there were no significant differences by birth order, twinning, or ethnic group. The CD4(+) percentage declined from birth to age 2 years, at which time it started to increase to higher levels at age 4 to 5 years. The CD8(+) percentage increased gradually from early infancy to age 2 to 4 years. The leukocyte count peaked at age 12 to 23 months and declined thereafter, whereas the lymphocyte percentage peaked at age 1 to 5 months and declined gradually thereafter. Compared with dry-season results, the lymphocyte percentage, the absolute lymphocyte count, the absolute CD4(+) T-lymphocyte count, and the CD4(+)/CD8(+) ratio were significantly lower during the rainy season, whereas the CD8(+) percentage was increased during the rainy season. Girls had higher CD4(+)/CD8(+) ratios and lower CD8(+) percentages than did boys. Conclusions: Compared with the limited data on T-lymphocyte subsets available from healthy children in developed countries, Guinean children have markedly lower CD4(+) percentages and CD4(+)/CD8(+) ratios and higher lymphocyte percentages during the first 2 years of life, when the pressure of infections is particularly high in Africa.