Figure 1. PD-L1 protein and mRNA detection using chromogenic immunohistochemistry and quantitative fluorescence in cell lines and human tissues.
(a) Representative microphotographs showing PD-L1 protein expression using diaminobenzidine (brown chromogen, upper panels), immunofluorescence (red channel, middle panels) and fluorescent in situ PD-L1 mRNA (red channel, bottom panels) in human placenta, PD-L1 expressing Mel624 cells and parental Mel624 cells, × 400 magnification. Bar=60 μm. (b) PD-L1 protein and mRNA fluorescence measurements in several areas of FFPE preparations containing parental Mel624 (Mel624 (−)), PD-L1 Mel624 transfectants (Mel624 (+)) or human placenta. Each dot shows the fluorescence score within the mask in an independent field of view and scores are expressed as arbitrary units (AU). ***P<0.001, NS, not significant, (c) Representative fluorescence microphotographs of PD-L1 protein (left panels) staining in a positive (histospot 142) and negative NSCLC sample (histospot 274). Right panels show representative in situ PD-L1 mRNA staining in a positive (histospot 315) and a negative (histospot 70) NSCLC case. Nuclei were stained with DAPI. × 400 magnification. Bar=100 μm.