Lymphocyte subsets in whole blood and isolated mononuclear leucocytes of healthy infants and children.

The determination of lymphocyte subsets utilizing monoclonal antibodies and flow cytometry has become essential in the evaluation of immunological status. Using a standardized method it was found that in healthy children the percentage of CD 8+ (Leu 2+) positive cells increases significantly (P less than 0.01) during infancy, whereas the percentage of CD 4+ (Leu 3+) positive cells decreases with age (P less than 0.01). The percentage of CD 3+ (Leu 4+) cells remains constant. The ratio of CD 4/CD 8 positive cells is significantly (P less than 0.001) higher in infants than in older children. Other subpopulations (HLA DR+, Leu 7) were found to be constant in all age groups. For the comparison of data on lymphocyte subsets obtained by flow cytometry a standardized test procedure is important.