Studies on the Mechanism of Prolonged Survival of Allografts from Tumor-bearing Donors1

The H-2 isoantigenicity of murine tissues was unaffected by the intraperitoneal growth of the Ehrlich ascites tumor, as shown by their normal capacity to absorb H-2 isohemagglutinins. Skin grafts from Ehrlich ascites tumor-bearing C57BL mice had a longer survival in RIII mice than grafts from nor mal donors. First-set allografts from tumor-bearing donors effectively immunized the hosts against second-set allografts from normal donors. Second-set allografts from tumor-bearing mice showed a prolonged survival in mice presensitized by firstset allografts from either normal or tumor-bearing donors. It therefore seems that the prolonged survival of skin allografts from tumor-bearing donors is not due to their decreased antigenicity or deficient immunogenicity, but rather to their in creased resistance to the allograft reaction of the host.