SDC1 and systemic lupus erythematosus: Furthermore, patients who developed severe flares displayed less prominent relative to baseline decreases through week 24 in CD19+CD20-CD138+ long-lived plasma cells (-23.5% versus -39.4%; P=0.028), CD19+CD20+CD138+ short-lived plasma cells (21.5% versus -41.1%; P=0.024) and CD19+CD27brightCD38bright SLE-associated plasma cells (-19.0% versus -27.8%; P=0.045) compared with patients who did not develop severe flares.