AGE-RELATED-CHANGES IN LYMPHOCYTE-T AND LYMPHOCYTE-B SUBPOPULATIONS IN THE PERIPHERAL-BLOOD

Abstract

Quantitation of T and B lymphocytes in infants and children is an important test in the diagnosis of a suspected immunodeficiency. Previous studies indicated that the absolute and relative numbers of lymphocyte subpopulations vary with age but these data in the pediatric age group are incomplete and often contradictory. The literature was reviewed and the relationship between age and lymphocyte subpopulations investigated in healthy infants and children using common methods and recent methodologic improvements. Absolute numbers of T and B cells followed the same trend as the total lymphocyte count, which was elevated at birth, increased in the 1st 6 mo., and then gradually decreased to adult levels at .apprx. 13 yr of age. Compared with adult values, the percentage of B cells also was higher at birth and continued to increase for 6 mo., followed by a gradual decrease to adult levels by late childhood or early adolescence. The percentage of T cells gradually increased to adult levels by the same age range.