The role of the peritoneal cavity in successful treatment of a murine lymphoma with chemotherapy and non-specific immunostimulation.

The influence of the route of administration and treatment schedule of a yeast immunoadjuvant, Candida albicans (CA) on the degree of success achieved with an immunochemotherapy regimen in a virus-induced murine lymphoma has been evaluated. To this end, histocompatible CD2F1 mice received IP or IV inoculations of LSTRA lymphoma cells and were subjected to various treatments with inactivated CA and bis,1,chloroethyl nitrosourea (BCNU). The results showed that CA may significantly increase the antitumor efficiency of BCNU when (a) the tumor is inoculated IP and not IV; (b) CA is administered before (on day -14) and after (on days +1 and/or day +8) LSTRA challenge; (c) CA is given IP as a post-tumor treatment. To ascertain whether the immunoadjuvant effect was anatomically restricted to the peritoneal cavity (PC), spreading of IP injected lymphoma was studied by means of LSTRA cells labeled with 3-5'iodo-deoxyuridine 125I (125IUdR) and tumor bioassay in spleen, lung, kidney, liver, and PC of recipient mice. The results showed that IP tumor challenge led to early (1 h) generalized neoplasia in both untreated and CA-pretreated hosts. Therefore, the combined antitumor effects of chemotherapy and CA are not restricted to the PC but rather the result of systemic immunity. In conclusion, in our system the PC seems to be a preferential site for eliciting generalized antilymphoma host responses markedly amplified by selected schedules of immunoadjuvant administration.