Effect of Neo-Natal and Adoptive Immunization on Tumor Transplant Susceptibility in Mice. ∗

Summary

1. A strain of mice resistant to the transplanted CD/5 lymphoma (DBA/2), and a tumor susceptible strain (BALB/C), were rendered mutually graft-tolerant by neonatal cross-immunization with spleen cells. At 6–8 weeks mice of both strains were injected subcutaneously with CD/5 lymphoma, which is isologous in BALB/C mice. Growing tumors in BALB/C mice were then challenged by an “adoptive” immunization procedure using spleen and lymph nodes from resistant DBA partners. 2. Neo-natally cross-immunized BALB/C mice were more resistant (45%) to the tumor than control animals (13%). 3. Following adoptive immunization, complete tumor regression was observed in 20% and partial regression in 25% of tumor bearing animals. Corresponding figures for a control group of normal BALB/C subjected to the same adoptive immunization were: complete regression (0%), partial regression (8%). 4. Antibody titers in DBA/2 mice against tumor protein did not correlate with tumor rejection. Neo-natally cross-immunized DBA/2 mice were less resistant to tumor (91%) than normal DBA/2 (100%). Antibody titer was minimal or absent in tumor resistant DBA/2 mice, but high in those cross-immunized mice accepting the tumor.