Induction of a tumor-specific immunity by re-transplantation of conditioned macrophages

Syngenic macrophages "conditioned" in the supernatant of a S-180 sarcoma cell culture were applied to mice. When inoculating S-180 cells into these mice later, they only rarely developed a tumor of smaller size compared to control animals which had not previously received conditioned macrophages. To achieve such an adopted immunity, it is important to keep the time short between trypsinization of macrophages and their injection to the host. Since human macrophages can easily be obtained, this method may present a perspective for tumor prevention in man.