Granulomonocyte colony-forming cells in cord blood.

The number of colony-forming cells (CFC) in cord blood has been found to be widely dispersed (478 +/- 1003/ml or 3-5200). However, a few samples (7 of 37 in this series) contained more than 478 CFC/ml and in four of these cases a history of prenatal hypertension or infection was found. In the other 30 cases the mean number of CFC was 140.6 +/- 116.9/ml blood (3-390), which, however, remains much higher than data found for adult blood. In these 30 cased the mean number of cord blood CFC in newborns of less than 37 weeks gestational age was found significantly higher (194.2 +/- 125.8/ml) than in full-term babies (99.7 +/- 93./ml, P less than 0.025). Cord blood CFC were shown to be early developing, high cycling cells. Velocity sedimentation separation showed only one population of CFC in blood with low cloning efficiency similar in size to adult blood CFC, but with a higher suicide level. Two populations of different sizes were separated in cord blood with high cloning efficiency, the larger cell population being similar to the adult bone marrow, early developing CFC. In premature newborns and in some perinatal conditions, hematopoiesis is characterized by a high level of circulating CFC with the appearance of a population of large cycling cells. The relationship between these findings and neonatal hematology is discussed.