Photodynamic therapy of murine mastocytoma induces specific immune responses against the cancer/testis antigen P1A
Menée sur un modèle murin, cette étude montre que la thérapie photodynamique induit une réponse immunitaire spécifique contre l'antigène tumoral P1A du mastocytome p815
Photodynamic therapy (PDT) involves the i.v. administration of photosensitizers followed by illumination of the tumor with visible light leading to local production of reactive oxygen species that cause vascular shutdown and tumor cell death. Anti-tumor immunity is stimulated after PDT due to the acute inflammatory response that involves activation of the innate immune system leading to stimulation of adaptive immunity. We carried out PDT using benzoporphyrin derivative and 690-nm light after 15-minutes, in DBA/2 mice bearing either the mastocytoma, P815, that expresses the naturally occurring cancer/testis antigen P1A, or the corresponding tumor P1.204 that lacks P1A expression. Tumor cures, significantly higher survival and rejection of tumor rechallenge were obtained with P815, that were not seen with P1.204, or seen with P815 growing in nude mice. Both CD4 and CD8 T-cells had higher levels of intracellular cytokines when isolated from mice receiving PDT of P815 tumors compared to P1.204 tumors, and CD8 T-cells from P815-cured mice recognized the peptide epitope of P1A-antigen (LPYLGWLVF) using pentamer staining. Taken together, these findings show that PDT can induce a potent antigen- and epitope-specific immune response against a naturally occurring mouse tumor antigen.