CD274 and Autoimmunity: This feature is not only crucial with regard to lack of interference with physiological tolerance signaling — e.g., in the intestine or placenta — but is of particular relevance in the context of autoimmunity and chronic inflammation, as PD-L1 expression is stimulated by inflammatory cytokines and upregulation of PD-L1 has been observed in certain autoimmune diseases, such as type 1 diabetes (38).