Activity of syngeneic complement for revealing antibody-induced cytotoxicity against a rat hepatoma

The cytotoxicity of tumour-bearer serum against a transplanted aminoazodye-induced rat hepatoma was revealed using normal rat serum as the source of complement as assessed using a short-term 51Cr release test. The tumour-bearing rat was not deficient in a functional complement system and direct cytolysis against hepatoma cells was demonstrated following admixture of tumour cells and serum with no additional complement. No tumour growth was observed in animals receiving subcutaneous transfer of cells treated with tumour-bearer serum, although when heat-inactivated (56 C for 60 min) or normal sera were used, there was no modification of tumour development. The present findings indicate that the tumour-bearing animal contains both antibodies and complement sufficient for tumour lysis, although the full contribution of serum-mediated cytotoxicity in imposing immunological constraints upon tumour growth remains to be elucidated.