Stabilization of tumor antigens by chemical modification with diethyl pyrocarbonate.

C3H mice were immunized with MH134 tumors modified with two different chemicals, DEPC and TNBS, and the tumor-neutralizing activities of the spleen cells were examined after separating the cells by a Nylon-wool column, plastic dish, or treatment with specific antibodies (anti-mouse IgG and anti-mouse theta sera). The effector cells induced in mice by immunization with TNBS-treated tumors were T cells. In contrast, in the case of tumors modified with DEPC, macrophages were the major effector cells. The effects of chemical modification on the solubilization of cell surface proteins was also examined. DEPC inhibited solubilization of specific proteins from tumor cell surfaces, while TNBS did not have such an effect on the solubilization of proteins. These results indicate that the antitumor response in mice primed with DEPC-modified tumor is different from the case of TNBS-modified tumors, and that the immunological significance of chemical modification with DEPC is supposedly due to the stabilization of antigenic proteins on the tumor cell surface.