Modification of the Immune Response of Mice to Skin Homografts and Heterografts by Ehrlich Ascites Carcinoma.

The immunological response of mice given implants of Ehrlich ascites carcinoma was modified as evidenced by the failure of ascitic mice to reject primary or secondary skin homografts or rat skin heterografts. The site of tumor implantation influenced its effect on the host, since subcutaneously implanted Ehrlich ascites carcinoma did not alter the immune response. The presence of the tumor in the ascites form resulted in the prolongation of survival of primary homografts by preventing the initial response of the host to the graft anti gens. This inhibition of the initial interaction between the host and the primary homograft antigens was evidenced by the observation that lymph nodes obtained from mice following simultaneous implantation of tumor in the ascites form, and a primary homograft, had not been sensitized by the primary homograft antigens, since such lymph nodes were not capable of passively eliciting a secondary homograft response when transplanted into normal isologous hosts. Secondary homograft or heterograft survival time on ascitic hosts was prolonged as a result of an inhibition of the reaction between the previously sensitized host and the graft antigens. Possible mechanisms by which the ascitic tumor caused these inhibitions are discussed.