mRNA expression of PD-L1 also increased upon treatment with 1,25(OH)2D3 in IL1β-stimulated monocytes in HC as well as in both APS-2 patient cohorts [AD/AITIL1β vs IL1β/1,25(OH)2D3 p = 0.006; T1D/AITIL1β vs IL1β/1,25(OH)2D3 p = 0.003; HCIL1β vs IL1β/1,25(OH)2D3 p = 0.006]. Here, CD274 is linked to type 1 diabetes mellitus.