An in-vitro quantitative study of phytohaemagglutinin (PHA) induced transformation of lymphocytes from premature newborn infants, from older premature infants, and from full-term newborn infants.

Abstract

The in-vitro transformation rate of blood lymphocytes induced by PHA was studied quantitatively by a microculture technique in combination with a cell counting procedure in full-term and premature newborn infants and in older premature infants at the time of their calculated birth dates. The number of cells in culture after 72 hours and the number of transformed cells were expressed as ratios of the original number of blood lymphocytes with which the cultures had been set up. Culture cell and transformation ratios of premature newborn infants were significantly larger than in adult controls and in older premature infants. Both ratios of the cultures from full-term infants were also significantly larger than in adults. Ratios of PHA cultures from older premature infants did not differ from those of adult cultures, but they were significantly lower when compared to the premature newborn group. Ratios from all infant groups showed significantly greater variations from their respective mean values than in adult cultures. These data are relevant to the ontogeny of the human lympahtic system.