Granulocyte-macrophage progenitor cells in term and preterm neonates.

In groups of adults, and term and preterm neonates, we determined: the blood concentration, the proliferative rate, and the variety of progeny of committed granulocyte-macrophage progenitor cells (CFU-GM). In five of eight term neonates and in all premature infants, a potentially significant limitation of neutrophil production was detected. Unlike the slowly proliferating CFU-GM present in the blood of healthy adult subjects (7% thymidine suicide, range 0% to 32%), the circulating CFU-GM in the premature subjects were proliferating at a near maximal rate (55%, range 40% to 75%, P less than 0.001). Because CFU-GM proliferation is nearly maximal in the baseline, noninfected state, neonates may have restricted ability to increase neutrophil production from CFU-GM during times of increased neutrophil need, such as during bacterial infection. Such inability may predispose neonates to exhaustion of the neutrophil supply during bacterial infection.