Immunotherapy of tumors with xenogeneic endothelial cells as a vaccine.

The breaking of immune tolerance against autologous angiogenic endothelial cells should be a useful approach for cancer therapy. Here we show that immunotherapy of tumors using fixed xenogeneic whole endothelial cells as a vaccine was effective in affording protection from tumor growth, inducing regression of established tumors and prolonging survival of tumor-bearing mice. Furthermore, autoreactive immunity targeting to microvessels in solid tumors was induced and was probably responsible for the anti-tumor activity. These observations may provide a new vaccine strategy for cancer therapy through the induction of an autoimmune response against the tumor endothelium in a cross-reaction.