CD28 and autoimmune pancreatitis: The spontaneous development of AIP in T-cell-competent HLA-DR*0405 transgenic Ab0 NOD mice [49], Treg-deficient backgrounds in neonatally thymectomized mice [54], NOD.CD28 knockout mice [51], and Tgfbr2fsp knockout mice [50] have demonstrated genetic polymorphisms of the effector cells in the etiologies of AIP.