Multicolor kit

For the mIHC staining in this study, primary antibodies (detailed information showed in supplementary Table 3) as well as a multicolor-kit (Absin, China) were used. We used Opal 520 channel for PD-L1 [fluorescein isothiocyanate (FITC), a green fluorescence stain], Opal 570 channel and Opal 670 for HLA-DR [cyanine 3 (Cy3), an orange fluorescence stain for Fig. 6. cyanine 5 (Cy5), a red fluorescence stain for Fig. 5.], Opal 670 channel for FEN1 [cyanine 5 (Cy5), a red fluorescence stain], and DAPI (4′,6-diamidino-2-phenylindole, a blue fluorescence stain). All the 20 slides were observed and imaged by Olympus FV1200 confocal system (Tokyo, Japan). All the images were analyzed by ImageJ software (NIH, Bethesda, MD, USA).

For the mIHC staining in this study, a multicolor-kit (Absin, China) was used as previously described [35 (link)]. We used the Opal 520 channel [fluorescein isothiocyanate (FITC), a green fluorescence stain], the Opal 570 channel [cyanine 3 (Cy3), an orange fluorescence stain], and the Opal 670 channel [cyanine 5 (Cy5), a red fluorescence stain] to locate different proteins (as detailed in the figure legends). DAPI was used for nuclear staining. All the slides were observed and imaged with an Olympus FV1200 confocal microscope (Tokyo, Japan).