P2RY8 and systemic lupus erythematosus: Moreover, a similar downregulation of P2RY8 in DN B cells (but not in T cells) was seen in AU non-Asian SLE patients with renal involvement (Fig. 6 G and Fig. S4 B), suggesting that P2RY8 downregulation can be extrapolated to non-Chinese SLE and appears to serve as a biomarker of renal lupus.