Blood colony-forming cells (CFU-C) and leucocyte colony-stimulating activity (CSA) in patients with neutrophilic leucocytosis.

The incidence of circulating colony-forming cells (CFU-C) and the ability of peripheral leucocytes to stimulate the colony formation (CSA) have been studied through a double layer agar culture system in 26 patients with neutrophilic leucocytosis and compared to the values obtained in 26 normal subjects. Both mean CFU-C incidence and mean leucocyte CSA of the whole group of patients were found significantly higher than normal, but considerable variation was observed among singular patients. The different patterns of blood CFU-C and leucocyte CSA are discussed. The combined evaluation of blood CFU-C and leucocyte CSA is found a useful tool to investigate the pathogenetic mechanisms of neutrophilic leucocytosis.