Glucocorticoid-induced appearance of the macrophage subtype RM 3/1 in peripheral blood of man.

The effect of intravenous administration of the glucocorticoid prednylidene on the macrophage subtype RM 3/1 in the peripheral blood of man was studied. Injection of 60 mg steroid resulted in an increase in the proportion of RM 3/1 positive monocytes 12 h after application from the basic level to about 80%. After 24 h the number of RM 3/1 positive cells decreased but remained elevated over the basis rate for a period of at least 15 days. Similar results were obtained after administration of 30 or 6 mg prednylidene even if the peak value occurred with a delay of 12 h after 6 mg. A dose- and time-dependent induction of the RM 3/1 positive subtype could also be demonstrated in vitro by the addition of prednylidene or dexamethasone to cultured purified human monocytes/macrophages. Deoxycortone or indomethacin had no effects. These results suggest that glucocorticoids exert their influence on cells of the mononuclear phagocytic lineage by inducing a distinct monocyte/macrophage subpopulation which seems to be associated with anti-inflammatory functions.