Changes in lymphocyte sub-populations in the blood of healthy and sick newborn infants.

Normal values for the percentages of lymphocytes carrying surface membrane-bound immunoglobulin, or rosetting with sheep erythrocytes, ox erythrocytes coated with rabbit immunoglobulin G, or ox erythrocytes coated with rabbit immunoglobulin M and reacted with human serum partially de-complemented with zymozan, have been estimated for populations from human umbilical cord blood and the peripheral blood of babies aged one week and one month. These samples have been compared with values obtained from normal adult volunteers and eighteen newborn infants, measured during and after a suspected infective episode. The dynamic change in those lymphocytes from normal infants staining for both IgM and IgD is shown, demonstrating that the number of circulating cells of this typeapproaches adult levels by the age of one month. Falls in the levels of all three types of rosetting lymphocyte were demonstrated over the same period. A drop in the number of lymphocytes forming sheep erythrocyte rosettes, and particularly those binding C3b-coated ox erythrocytes, in those babies suspected of infection showed a correlation with acute septicaemia or viraemia.