CD274 and rheumatoid arthritis: By measuring the levels of PD-L1 in different subsets of Bregs, that is, CD19+ PD-L1+ B cells, CD24hi CD38- PD-L1+ B cells, and CD24hi CD38hi PD-L1+ B cells, the authors noted that all cells having the highest levels of PD-L1 were significantly reduced in rheumatoid arthritis patients when compared to the healthy controls.