2.9 Hematoxylin and eosin (H&E) staining and immunofluorescence
The tumor tissue was fixed with 4% formalin, embedded in paraffin, and cut into 4 µm sections. The sections were stained with H&E. Immunofluorescence analysis was performed with slight modifications based on the method described by Dai18. Briefly, sections were dewaxed and rehydrated. We used citrate antigen retrieval solution for antigen repair (12 min), 3% H2O2 for inactivation of endogenous peroxidase (10 min), and 3% BSA for blocking (15 min). Slices were then incubated with rabbit anti-mouse CD11b and rat anti-mouse CD206 (Abcam, Cambridge, UK) antibodies overnight at 4 °C. Next, the cells were incubated with goat anti-rat IgG-TR and goat anti-rabbit IgG-FITC secondary antibodies. Cells were incubated with DAPI for 40 min at 37 °C. Finally, slides were observed and photographed using a fluorescence microscope.