VARIATIONS IN GRANULOCYTE COLONY-FORMING CELL NUMBERS IN ADULT-BLOOD

Summary. Blood granulocyte colony forming units (CFU‐C) were studied in normal adults to establish: (i) a normal range; (ii) variability due to the culture technique; (iii) variability of blood CFU‐C within individuals. Thirty men studied had 98 (range 8–300) CFU‐C × 103/1, and 28 women studied had 44 (range 0–260) CFU‐C × 103/1. This difference was significant (P<0.001). There was also a significant sex difference in the total number of cells forming colonies and clusters per litre; and in the incidence of colony formers and of cluster formers in buffy coat and mononuclear cell blood fractions. CFU‐C were assayed in four subjects over a 10 week period. When buffy coat cells were used as a source of colony stimulation the week to week variation in the combined growth of the four subjects was wide (±36%) but with conditioned medium the variation was smaller (±14%). In all subjects colony and cluster growth varied in the same way (r=0.77, P=0.001) but there was no correlation with the total leucocyte count. A 3–4 week cyclical change in CFU‐C/1 was found which was independent of the variation inherent in the technique. The physiological significance of the sex difference and the apparent cyclical changes in blood CFU‐C are not explained, but the results emphasize the wide fluctuations in CFU‐C that may occur in normal individuals. Copyright © 1979, Wiley Blackwell. All rights reserved