ERYTHROMYCIN PROMOTES MONOCYTE TO MACROPHAGE DIFFERENTIATION

Recent reports have suggested that long-term administration of erythro mycin (EM) appears to ameliorate some of chronic inflammatory processe s where macrophages and lymphocytes pity important roles. Our study wa s initiated to examine the effect of EM on monocyte-macrophage lineage in vitro. EM (1 similar to 100 mu g/ml) significantly increased the n umber of adherent monocyte-derived macrophages after 7 days of culture . The combination of EM and macrophage colony stimulating factor (M-CS F) synergistically increased the number of monocyte-derived macrophage s, while the combination of EM and granulocyte-macrophage colony stimu lating factor exerted an additive effect. Culture with EM induced the expression of a surface antigen CD71, one of the activation markers of macrophages as compared with control cultures. The combination of EM plus M-CSF significantly enhanced H2O2-producing capacity of those cel ls as compared with M-CSF alone. A differentiation process of monocyto id THP-1 cells was also augmented by EM. These results indicate that E M promotes differentiation of human monocyte-macrophage lineage, alter ing their functions.