Tumor‐specific transplantation antigens in spontaneously transformed hamster cell lines

Spontaneously transformed hamster cells were examined for the presence of TSTA by employing the tumor rejection test. It was demonstrated that each of the spontaneously transformed cell lines as well as cells derived from tumors induced by these cells possess an individual distinct antigen, capable of evoking a significant anti‐tumor immunity. The immunizing potential of these antigens and their specificity were not affected by either in vivo or in vitro environment. The results suggest that the spontaneously transformed hamster cells undergo antigenic modification, which resembles the TSTA of chemical‐carcinogen induced tumors.