More on the relevance of animal tumor models: immunogenicity of transplantable leukemias of recent origin in syngeneic strain 2 guinea pigs.

The immunogenicity of four transplantable leukemias was evaluated in syngeneic Sewall-Wright strain 2 guinea pigs. The L76 and KSL leukemias are considered appropriate models for the assessment of immunogenicity because of their recent origin and unknown (natural) etiology. The chemically induced K77 leukemia of recent origin and the long-passaged L2C leukemia of unknown etiology could be classified as experimental tumors prone to artifactual immunogenicity. Our studies clearly show that naturally occurring guinea pig leukemias are potentially immunogenic, although to a lesser degree than experimental leukemias. These findings are in contrast to previous studies in mouse and rat tumor models, which showed that naturally occurring tumors were essentially nonimmunogenic, thereby raising questions about the relevance of animal tumor models to human cancer.