LLC cells (2×106 in 100 μL PBS) were subcutaneously injected into the right flank (as primary tumor) on day 0 and in the left flank (as abscopal tumor) on day 3 of each male mouse with different PD-L1 status. The tumor volume on both flanks was measured every two days after injection and calculated with a formula V = (width2×length)/2. When tumor volume reached to about 50 mm3, the primary tumor was locally exposed to X-rays (X-RAD 320, PXI, USA) with 24 Gy in 3 fractions in 3 successive days (day 10, 11, and 12 after cell injection).
For the treatment with an autophagy inhibitor hydroxychloroquine (HCQ) (MedChemExpress, Monmouth Junction, NJ, USA), HCQ (50 mg kg−1 in 100 μL saline) or its saline control was injected intraperitoneally (i.p.) into tumor-bearing mice at 2 h before each IR. For blocking type I interferon (IFN-I), anti-IFNAR1 (500 μg, BioLegend, San Diego, CA) was administrated intraperitoneally into each mouse on day 9 of cell injection i.e., one day before tumor IR.
For the treatment with an autophagy inhibitor hydroxychloroquine (HCQ) (MedChemExpress, Monmouth Junction, NJ, USA), HCQ (50 mg kg−1 in 100 μL saline) or its saline control was injected intraperitoneally (i.p.) into tumor-bearing mice at 2 h before each IR. For blocking type I interferon (IFN-I), anti-IFNAR1 (500 μg, BioLegend, San Diego, CA) was administrated intraperitoneally into each mouse on day 9 of cell injection i.e., one day before tumor IR.