Immunohistochemistry Analysis of PC Tumors

Immunohistochemistry assay was performed in human or mouse PC tumor tissues as previously described [21 (link)]. Briefly, tissues were sectioned into 4 μm thick sections from formalin-fixed and paraffin-embedded forms. After dewaxing, sections were incubated in 3% H₂O₂ solution for 30 min at room temperature to block endogenous peroxidase activities. Then, sections were microwaved for antigen retrieval in a citrate buffer. Sections were then incubated with primary antibodies CXCL14 (1 : 100), PD-L1 (1 : 100), and IL-10 (1 : 50) (Cell Signaling Technology, USA) at 4°C overnight. Slides were coverslipped after sample counterstaining. Five random regions in each section were selected to analyze under an inverted microscope. The cell images were analyzed by Image-Pro Plus 6 software (Media Cybernetics, USA).