Tumour‐specific antigenicity of aminoazo‐dye‐induced rat hepatomas

Tumour‐specific transplantation antigens have been demonstrated in rat hepatomas induced with 4‐dimethylaminoazobenzene (DAB). Resistance to these tumours was induced in syngeneic hosts either by destruction of developing tumour grafts or by implantation of heavily irradiated tumour. These rat hepatomas were shown to possess individual antigenicities so that induction of immunity against one hepatoma did not confer on the treated rat any resistance to a second hepatoma also induced by DAB. Resistance could be passively transferred to normal rats with peritoneal exudate cells from immune donors. These peritoneal exudate cells, containing approximately equal proportions of macrophages and lymphocytes, carried the same specificity as the immunizing tumour in that they were without influence on the growth of other DAB‐induced hepatomas.