Induction of tumoricidal activated macrophages by a liposome-encapsulated glycolipid, trehalose 2,3,6'-trimycolate from Gordona aurantiaca

A mycolic acid-containing glycolipid, trehalose 2,3,6'-trimycolate, prepared from a non-pathogenic acid-fast bacterium Gordona aurantiaca, was shown to induce strong tumoricidal activity in peritoneal exudate cells by intravenous or intraperitoneal injection of liposome-encapsulated preparations. The mycolic acid derivative containing a high proportion of unsaturated fatty acids rendered macrophages cytotoxic against syngeneic mastocytoma cells in the absence of endotoxin, for over 14 days after the injection. The macrophages were ascertained to be at low intracellular levels of a lysosomal enzyme beta-galactosidase and an ectoenzyme alkaline phosphodiesterase, a specific pattern as previously described for "primed macrophages". However the culture supernatants of the peritoneal exudate cells were not cytotoxic.