[Immunization against Trypanosoma cruzi and tumor growth in mice].

The evidence has been produced that immunological mechanisms are involved in the known anticancer phenomenon of T. cruzi. Non-inbred albino mice were immunized with avirulent cultures of three strains and seven clones and then transplanted a tumor--sarcoma-180 or Ehrlich's adenocarcinoma. The used cultures induced the generation of T. cruzi antibodies whose level peaked by postimmunization days 50-60: the titers being 1:40-1:80 and the spread among the mice being 60%. Concurrently, immunization against T. cruzi provided a certain oncoprotective effect. In the immunized mice, the sizes of sarcoma-180 and adenocarcinoma were 1.5-2.0 and 2.0-2.5 times, respectively, less than those in the non-immunized ones. The antitumor protection was directly related to the murine blood T. cruzi antibody level during which implantation of a tumor occurred. At the peak of an immune response, the effect was 2 times higher than that in the early postimmunization periods. T. cruzi strains that were more immunogenic than clones ensured a more significant oncoprotection. The latter was more considerable in mice having antibody titers of 1:40-1:80 than in those with antibody titers of 1:10-1:20 and particularly in the animals showing no humoral response to the administration of the parasites at all.