Figure 4.

Combination therapy with CIRT and anti-PD-1 enhances immune response. C57BL/6 mice bearing subcutaneous B16 and S91 melanom were injected intraperitoneally with anti-PD-1 (α-PD-1) or locally irradiated with 5 Gy of X-rays (XR) or 5 GyE of carbon ions (CIRT) at tumor sites or received combined treatment with 5 Gy of X-rays and anti-PD-1 (XR+α-PD-1) or 5 GyE of carbon ions and anti-PD-1 (CIRT+α-PD-1). Eight days after irradiation, we analyzed the proportions of CD3⁺CD4⁺ and CD3⁺CD8⁺ T lymphocytes in the spleen and tumor, and infiltrating MDSCs in the tumor by flow cytometric analysis. CD3⁺, CD4⁺, CD8⁺, and granzymeB⁺ infiltration in tumors were ascertained by immunohistochemistry. Representative images and quantification are shown (mean ± SD of triplicate assessments, Student’s t test, ***p < .001).