Comparison between diurnal changes and changes induced by hydrocortisone and epinephrine in circulating myeloid progenitor cells (CFU-GM) in man.

A significant increase from 8 AM to 3 PM was found in both myeloid progenitor cell (CFU-GM) and polymorphonuclear leukocyte (PMN) blood concentration in 45 normal subjects. Diurnal blood (CFU-GM and PMN changes were significantly correlated. Spontaneous diurnal changes in blood CFU-GM levels and in PMN were compared with the changes induced by i. v. administration of hydrocortisone (16 normal volunteers) and of epinephrine (10 normal volunteers). Diurnal changes in CFU-GM and PMN seem to follow a pattern similar to that induced by epinephrine administration. These findings suggest that diurnal changes in CFU-GM reflect mainly a shift of these cells between different blood compartments.