Figure 3.

Combination therapy with CIRT and anti-PD-1 stimulates immunogenic cell death. C57BL/6 mice bearing subcutaneous B16 and S91 melanoma (Model) were injected intraperitoneally with anti-PD-1 (α-PD-1) or locally irradiated with 5 GyE of carbon ions (CIRT) at tumor sites, or received treatment with 5 Gy CIRT plus anti-PD-1 (CIRT+α-PD-1). Eight days after irradiation, we examined CALR exposure, eIF2α phosphorylation, and HMGB1 exodus by immunofluorescence; secretion of IFN-γ in serum by ELISA; and IFN-γ infiltration in the tumor by immunohistochemical assay. Representative images and quantification are shown (mean ± SD of triplicate assessments, Student’s t test, ***p < .001).