CD4 and bile duct papillary neoplasm: However, this stepwise decrease of CD4+ and CD8+ infiltrates in BilIN-associated carcinogenesis was not mirrored in IPN-associated cholangiocarcinogenesis, in which the decrease of CD4+ and CD8+ T cells occurred mainly in IPN and was not observed in the transition to invasive BTC (Figs. 3d and  4e–g).