T-LYMPHOCYTE SUBSETS IN WEST-AFRICAN CHILDREN - IMPACT OF AGE, SEX, AND SEASON

Objective: There has been no reference material for T-lymphocyte subse ts for normal children in developing countries. We therefore used T-ly mphocyte subset determinations among children in three different studi es 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 wer e included in the three community studies of T-lymphocyte subsets amon g twins and singletons, after measles infection and after measles immu nization. We used the immunoalkaline phosphatase method to determine T -lymphocyte subsets. Results: We found differences by age, sex, and se ason, whereas there were no significant differences by birth order, tw inning, 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 p eaked at age 1 to 5 months and declined gradually thereafter. Compared with dry-season results, the lymphocyte percentage, the absolute lymp hocyte count, the absolute CD4(+) T-lymphocyte count, and the CD4(+)/C D8(+) 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 boy s. Conclusions: Compared with the limited data on T-lymphocyte subsets available from healthy children in developed countries, Guinean child ren have markedly lower CD4(+) percentages and CD4(+)/CD8(+) ratios an d higher lymphocyte percentages during the first 2 years of life, when the pressure of infections is particularly high in Africa.