Modulation of tissue mononuclear phagocyte clonal growth by oxygen and antioxidant enzymes.

We have investigated the effects both of oxygen concentrations below that of ambient air in the gas phase and antioxidant enzymes on the clonal growth of various tissue mononuclear phagocyte colony-forming cells in vitro. The degree of enhancement in growth is dependent on the source of these colony-forming cells. Clonal growth of colony-forming cells from peritoneal exudate was enhanced both by lowering the oxygen tension and using three antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase). The optimal concentration of oxygen was 6%. Colony-forming cells from alveolar spaces failed to respond to either the reduction in oxygen tension or the addition of antioxidant enzymes to the culture dishes. The optimal concentration of oxygen for the clonal growth of blood monocytes was 6%. However, clonal growth was enhanced more in soft agar than in liquid culture. Our data also suggest that at least part of the growth-enhancing effect of hemolysate may be attributable to its ability to decrease oxygen toxicity.