Background: Since the growth state of macrophages in local pathological sites is considered a factor that regulates the processes of many disease, such as tumors, inflammation, and atherosclerosis, the substances that regulate macrophage growth or survival may be useful for disease control. We previously reported that securiosides A and B, novel triterpene saponins, exerted macrophage-oriented cytotoxicity in the presence of a L-cell-conditioned medium containing macrophage colony-stimulating factor (M-CSF), while the compounds did not exhibit an effect on macrophages in the absence of the growth-stimulating factors.