T lymphocyte subpopulations in high-risk infants: influence of age and blood transfusions.

Methodology was established to analyze T lymphocytes and T cell subsets with monoclonal antibodies on microsamples of blood obtained by heel puncture in infants. Results in 39 high-risk infants indicated that during the early neonatal period they had a higher percentage of T4-bearing cells and a lower percentage of T8 antigen-positive cells as compared with adults. These values progressively approached adult values, and at 3 to 7 months the T cell subsets and the T4/T8 ratios were within the adult range. A significant inverse relationship was noted between the number of blood transfusions given to the infants between 2 and 12 weeks of age and the corresponding T4/T8 ratio. These findings suggest that interpretation of T cell subsets in frequently transfused infants should take into consideration not only the age of the infant but also the possible influence of transfusions per se on the distribution of T cell subsets in the peripheral blood.