Mobilization of colony-forming cells (CFU-C) into the peripheral blood of man by hydrocortisone

: The effect of hydrocortisone on blood CFU-C has been studied in six normal subjects through a double layer agar culture system. Increased numbers of CFU-C appeared in the peripheral blood reaching a maximum 366% to 631% increase 5-8 hours after the i.v. administration of the hormone. Contemporary lymphopenia caused a 4 to 10 fold enrichment in the proportion of CFU-C to lymphocytes. Hydrocortisone added in vitro somewhat inhibited the colony growth. The results suggest that the increase of blood CFU-C is due to mobilization from the bone marrow. Hydrocortisone, when compared to other agents, appears to offer some advantages in increasing the blood CFU-C for clinical purposes.