CD274 and Crohn disease: The anticipated in vivo function of endogenously-formed AMCP may require this inert (silent-delivery) nature of the cargo-bearing particles because the default setting for gastrointestinal immune cells is one of hyporesponsiveness and tolerance towards non-self antigens.39, 40 While the AMCP is inert, its cargo (notably peptidoglycan) appears to actively promote tolerance in the normal gut by up-regulating the co-regulatory molecule, PD-L1, on APCs that are recipients of endogenous cargo-bearing AMCP.17, 33 However, this is not the case in Crohn's disease.41