CD4 and pancreatic intraductal papillary-mucinous neoplasm: To identify the specific immune cell types involved in IPMN progression, CD20 (B cells), CD4 (helper T cells), CD8 (cytotoxic T cells), Foxp3 (Treg cells), CD68 (macrophages), and CD11b (myeloid-derived cells), positive cells were analyzed by immunohistochemistry.