Changing transplantation characteristics with serial in vivo passage of C3H/He mammary carcinomas.

The transplantation immunogenicity of spontaneous C3H/He mammary carcinomas was studied by means of the surgery-challenge procedure during serial in vivo passages in syngeneic mice. Reciprocal cross-sensitization and challenge tests between late transplant generations and early transplant generations (from liquid N2 storage) of the same tumors showed that factors responsible for transplantation resistance and factors causing stimulated tumor growth were present in the tumors at the same time as independent variables. The immunogenicity and the immunosensitivity of tumors were seen as dependent variables. The relative prominence of the characteristics of immunogenicity and growth stimulation changed with continuous in vivo passages. Transplantation immunogenicity was tumor specific in four of five tumors tested. Growth stimulation was, in each of four combinations tested, not tumor specific.