Enhancement of in vitro and in vivo antitumor activity by cord factor (6-6'-dimycolate of trehalose) administered suspended in saline.

The antitumor activity of trehalose-6,6'-dimycolate (TDM) dispersed in saline was studied in vitro and in vivo. In vitro, macrophages from TDM-treated mice entirely abolish, even at a 1.25:1 effector/target cell ratio, the (3H)TdR incorporation of P815 mastocytoma cells to the culture in which they were added. In vivo, the number of P815 cells harvested 10 days after their injection into TDM-treated mice was reduced by a factor higher than 50. The slopes of the radiolabel elimination of TDM-treated mice injected with 10(7) 125I-UdR-labelled L1210 leukemic cells were greater than those of untreated controls. The interest of such a compound which seems to be one of the active structures responsible for the antitumor activity of BCG is its efficiency when administered dispersed in saline.