Using enzymatic double-staining immunohistochemistry, we analysed CD8 + PD-1+ TILs and CD4 + FoxP3+ TIL counts in the stroma and intra-tumour in nine ICC patients selected based on high TILs in hematoxylin and eosin staining (Supplementary Fig 1). The gene discussed is CD4; the disease is intrahepatic cholangiocarcinoma.