Evolution of three lymphocyte markers in newborn, preterm infants.

Nine newborn, preterm infants have been studied at the ages of 1-3 days, 8-10 days and 22-24 days for surface markers on peripheral blood lymphocytes. As compared to adult controls, four of the infants had a low proportion of sheep RBC binding lymphocytes at birth, but at 1-3 weeks of age all infants had reached the adult level. Lymphocyte receptors for Fc of IgG and for complement, although both mainly characterizing non-T cells, evolved differently post partum: the proportion of Fc-receptor-bearing lymphocytes tended to increase with age of the infant, whereas already at birth complement receptor-bearing lymphocytes were at or above the adult level.