To determine whether PD-1 protein is a suitable target for PDAC immunotherapy we measured the level of PD-1 expression on tumour-infiltrating CD8+ T lymphocytes by immunohistofluorescence and on peripheral T lymphocytes by flow cytometry in healthy donors and patients with intraductal papillary mucinous neoplasm (IPMN) or PDAC. Here, PDCD1 is linked to pancreatic intraductal papillary-mucinous neoplasm.