Corticosteroid-dependent alterations of human myelopoiesis in vitro

We have demonstrated in this study that corticosteroids modify cellular interactions enhancing CSA production. This phenomenon may contribute to the leukocytosis-promoting action of these hormones, although at present it is unknown whether this mechanism is more important in vivo than steroid-dependent changes in the circulation and redistribution of phagocytic cells. The observation that corticosteroids impair phagocyte functions is difficult to reconcile with the well known fact that hypercorticism as a part of the normal body defense to stress (6). In view of our data it appears, however, that these possible detrimental effects of corticosteroids on mature white blood cells are counteracted by their stimulatory action on the production of new phagocytic cells. Such a conclusion is in accord with Joyce and Charvenick (20) who showed that those hormones enhance the return of GM-CFU in cyclophosphamide-treated mice and improve tolerance to infection.