Clodronate (dichloromethylene bisphosphonate) inhibits LPS-stimulated IL-6 and TNF production by RAW 264 cells

Effect of liposome-encapsulated and free clodronate on the IL-6 and TNF production by macrophages was studied using RAW 264 cell line as a macrophage model, and dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) for analysis of secreted cytokines. LPS-stimulated RAW 264 cells proved to produce notable amounts of these two cytokines, and DELFIA was sensitive and reliable method for analysis. Liposome-encapsulated clodronate inhibited the production of both cytokines, IL-6 being affected more than TNF, and the effect was mostly due to the drug itself, not to liposomal lipid. More than ten times higher concentration of free clodronate than liposomal clodronate was needed to inhibit cytokine production. This is the first report on the cytokine inhibitory property of clodronate, and the results support the idea of the use of liposomal clodronate as a macrophage suppressive agent in autoimmune diseases.