CTLA4 and familial pancreatic carcinoma: The immune‐suppressing mechanisms induced by Tregs are as follows: suppression of effector T cells by secreting immune‐suppressive cytokines such as TGF‐β or competing for IL‐2; induction of effector T‐cell apoptosis by cytotoxic enzymes such as granzyme B; and inhibition of dendritic cell maturation and function.30 In pancreatic cancer tissue, abundant Tregs are present.6 Cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4), which is constantly expressed on Tregs, plays a central role in suppressing antigen‐presenting cells.