[Antitumoral activation of rat peritoneal macrophages by muramyl dipeptide in vitro].

Muramyl dipeptide (MDP) is a synthetic adjuvant known to activate macrophages. We now report that rat peritoneal macrophages are rendered tumoricidal in vitro against tumor cells either when macrophages are preincubated for 24 hrs. with MDP or when MDP is added to the culture medium simultaneously with the tumor cells. MDP significantly increases the cytotoxic activity of macrophages activated in vivo with BCG.