Induction of antitumor immunity employing live tumor cells and maltose tetrapalmitate.

Several protocols employing a new immunoadjuvant, maltose tetrapalmitate (MTP), were tried in an effort to obtain immunization against a weakly immunogenic transplantable mammary adenocarcinoma, 13762, in syngeneic Fischer rats. Effectiveness of immunization was measured by rejection of tumor or reduction in tumor growth, by alteration in survival time after tumor challenge, and by proliferation in vitro of spleen cells of animals tumor-sensitized by killed tumor cells and tumor extracts. No success in the induction of tumor rejection was achieved by employing killed tumor cells or 3 M KCl tumor extracts used in either the presence or absence of MTP. Only a low dose of viable tumor cells elicited tumor rejection immunity when combined with MTP treatment given three times weekly. Spleen cell proliferation of tumor-sensitized animals was obtained in the case of live cells and 3 M KCl extract immunization, and was specific for the type of antigen (killed cells or soluble) preparation employed.