Fig. 1

Immune cell infiltration and PD-L1 expression in nasopharyngeal carcinoma. Representative images at × 200 magnification of nasopharyngeal carcinoma tissue sections showing a T-lymphocytes and their subsets b Tumor cells expression of PD-L1. The red color represents CD3 staining while CD8, FOXP3 (nuclear), PD-1 and PD-L1 are brown. Inset in the FOXP3 staining image shows a higher magnification image (× 530) to illustrate the membranous red CD3 staining and nuclear brown FOXP3 staining as a typical marker for T-reg cells. *Images of negative controls are shown in b, i.e., sections incubated with antibody diluent alone without primary antibody