Apart from autoimmune disorders, this pathway has been proven to be involved in the establishment of maternal-fetal tolerance26, 27, since PD-L1 blockade results in the reduction in litter size, number and increase in embryo resorption of mice, and the failure of fetal–maternal tolerance with Treg deficiency and hyperactivity of Th17 cells28. Here, CD274 is linked to autoimmune disease.