Influence of a macrolide antibiotic, roxithromycin, on mast cell growth and activation in vitro.

BACKGROUND: Long-term administration of macrolide antibiotics is recognized to be able to favorably modify the clinical condition of inflammatory diseases, such as diffuse panbronchiolitis and cystic fibrosis. However, the precise mechanisms by which macrolide antibiotics could improve clinical conditions of the patients are not well understood. AIM: The present study was designed to examine the influence of macrolide antibiotics on effector cell functions responsible for inflammation through the choice of roxithromycin (RXM) and mast cell. METHODS: Mast cells were induced by long-term culture of splenocytes from BALB/c mice. RXM was added to the cultures at seeding and then every 4-5 days, when the culture medium was replaced with a fresh one. The influence of RXM on mast cell growth was evaluated by counting the number of cells grown on the 16th day. We also examined the influence of RXM on mast cell activation by examining histamine release and inflammatory cytokine secretion. RESULTS AND CONCLUSION: RXM could not inhibit mast cell growth, even when splenocytes were exposed to 100 microg/ml of RXM throughout the entire culture periods. RXM also could not suppress histamine release from cultured mast cells in response to non-immunological and immunological stimulations. However, RXM could suppress inflammatory cytokine, interleukin-1beta, interleukin-6, granulocyte macrophage-colony stimulating factor and tumor necrosis factor-alpha, secretions induced by concanavalin A stimulation at a concentration of as little as 0.5 microg/ml. These results may suggest that RXM modulated the ability of mast cells to secrete inflammatory cytokines and results in improvement of clinical condition of chronic inflammatory diseases.