A RECOMBINANT LISTERIA-MONOCYTOGENES VACCINE EXPRESSING A MODEL TUMOR-ANTIGEN PROTECTS MICE AGAINST LETHAL TUMOR-CELL CHALLENGE AND CAUSES REGRESSION OF ESTABLISHED TUMORS

Listeria monocytogenes is an intracellular organism that has the unusu al ability to live in the cytoplasm of the cell. It is thus a good vec tor for targeting protein antigens to the cellular arm of the immune r esponse. Here we use a model system, consisting of colon and renal car cinomas that express the influenza virus nucleoprotein and a recombina nt L. monocytogenes that secretes this antigen, to test the potential of this organism as a cancer immunotherapeutic agent. We show that thi s recombinant organism can not only protect mice against lethal challe nge with tumour cells that express the antigen, but can also cause reg ression of established macroscopic tumours in an antigen-specific T-ce ll-dependent manner.