Photodynamic therapy boosts anti-glioma immunity in mice: a dependence on the activities of T cells and complement C3

Abstract

Photodynamic therapy (PDT) involves the systemic administration of a tumor-specific photosensitizer and local irradiation of visible light, can generate highly cytotoxic molecular species in the tumor and kill malignant cells directly or by shutting down the tumor microvasculature. Collectively data show that anti-tumor immunity is an important mechanism that mediates the PDT-induced tumor-destroying effects in many types of cancers. However, it is unknown whether PDT also promotes anti-tumor immunity in gliomas in the central nervous system (CNS). Here we show that the PDT generates regional and systemic anti-tumor immunity in mice with G422 gliomas in the brain. The infiltration of immune cells and the release of inflammatory factors, such as TNF-α and IFN-γ, are increased in animals with G422 gliomas following PDT when compared with those without receiving PDT. The lymphocytes that are isolated from PDT-treated mice are able to induce anti-tumor immunity in nude mice. The anti-glioma immunity fostered by PDT is inhibited in complement C3 knockout mice and the nude mice indicate the requirement of the activities of complement C3 and T cells. Thus, T cells that produce cytokines, along with complement C3, may play crucial roles in mediating PDT-induced anti-glioma responses.