PRDM1 and systemic lupus erythematosus: • SLE associated with 2 novel CXCR5-CD19low subsets (mBlow and DNBlow), with the following characteristics: • Plasmablasts-like transcriptional in DNBlow cells programming (IRF4, PRDM1, XBP1, EZH2 expression revealed using RNA-seq) • Diminished B cell receptor responsiveness • Phenotype: CD38+ CD95, CD71