Brief Communication: In Vivo Cortisone Sensitivity of Nonspecific Antitumor Activity of Corynebacterium parvum-Activated Mouse Peritoneal Macrophages

The nonspecific antitumor activity of Corynebacterium parvum-activated mouse peritoneal macrophages in vitro was inhibited by their prior treatment with cortisone acetate in vivo. Inhibition was marked (60 percent) 24 hours after cortisone injection and was still significant at 7 days, but antitumor activity was completely recovered by 9 days. This transient inhibition was sufficient to abolish the non-specific protection afforded by C. parvum in an in vivo pretreatment model.