Inhibiton by glucocorticoids and choleragen of the conditional growth of poorly adherent mononuclear phagocytes of newborn hamster liver and lung (Hormonal control of macrophage growth)

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Abstract
Conditions for in vitro growth of mononuclear phagocytes from newborn hamster liver and lung were studied. In the primary cultures of liver and lung, round cells outgrew and frequently floated off into the culture medium. They were separated from fibroblast‐like cells adherent to plastic by collecting the medium. The round cells were identified as mononuclear phagocytes on the criteria of phagocytic capacity of heat‐killed bacteria and IgG‐coated erythrocytes, fine cell structure and cytochemistry. The phagocytes that had not been activated previously proliferated for about ten generations in F12 medium supplemented with 10% fetal calf serum depending on a growth factor produced by hamster brain, liver or lung cells. Without the factor, the cells quickly cytolysed. Mononuclear phagocytes from blood had the same characteristics of growth and cytochemistry, but had fewer IgG receptors at the cell surface than similar cells from the liver and lung. The effects of a variety of chemical compounds on the growth of the liver and lung cells were studied. Insulin stimulated their growth by 20‐30%, but was not replaceable for the growth factor. Glucocorticoids, dexamethasone and hydrocortisone, inhibited the growth of the phagocyates at the physiological concentrations: 3 × 10−9M and 2 × 10−8M for 50% inhibition, respectively. Indomethacin, non‐steroid anti‐inflammatory reagent, at 10−8 M to 10−6M gave no effect. Choleragen that increases the intracellular cyclic AMP level, inhibited the growth at a concentration as low as 5 pg/ml. These data suggest that the growth of mononuclear phagocytes is controlled not only by a growth factor produced by other cells but also by glucocorticoids.