Basic studies on a new material for inducing antitumor immune cells. Recently, adoptive immunotherapy for cancer with lymphokine activated killer (LAK) cells has been widely used experimentally. The therapy has several problems, including difficulty in handling, sterilization, and time consumption. To solve these problems, new materials able to induce antitumor immune cells were investigated. Pokeweed mitogen (PWM) and PWM-conjugated materials (CMC-1) could induce strong killer cells by short-term stimulation of human peripheral blood lymphocytes (PBL). The induced killer cells showed a wide killing spectrum in vitro against human tumor cell lines (MKK-1, PRMI4788, NBT-2, ZR-7530, H-1, Hela, KB, HMV-1, PC-10, C-1). Human PBL stimulated for a short time by CMC-1 also showed a tumoricidal effect on tumor bearing (MKN-1, MKN-45) nude mice. These results suggest that CMC-1 may solve the problems with currently used LAK therapy and may provide easily applicable extracorporeal immunotherapy for cancer. 