The HSP70 Release Regulates the Immune Response of Tumor Cells in PDT Treatment

Heat shock protein70 (HSP70)is expressed plentifully in tumor cells, and it could regulate tumor immunity. Recent studies show that PDT induce cell surface expression and release HSPs from the treated cells. HSPs have critical role in PDT-induced immune responses, but the immune regulate mechanism of HSP70 and the dynamic of HSP70 interaction with macrophage induced by PDT have not been reported. In present study, YFP-HSP70 was used to monitor the dynamic distribution of HSP70 in real time. With confocal laser scanning microscope (LSM), we detected the dynamic of HSP70 distribution and the interaction with macrophage after PDT treatment. In order to further discuss the immune regulate mechanism of HSP70 after PDT, we also detected TNF-alpha released from macrophages induced by HSP70 with TNF-alpha ELISA. The results showed that PDT treated tumor cells captured by macrophages, and activated the macrophages and induced TNF-alpha release. In addition, the immune effect on overall expression HSP70 cells was higher than normal cells, and decreased evidently when HSP70 was blocked. Our data suggest that HSP70 may serves as a danger signal for immune cells and induce immune responses to regulate the efficacy of PDT.