Our data indicate a clinically relevant discrepancy in BCD between peripheral blood and the kidney in patients with LN with the persistence of interstitial B cells (as demonstrated by CD79- and Pax-5-positive cells), which was associated with progressive CKD and end-stage renal failure in four patients, whereas the patient with preserved renal function had no detectable B cells in the kidney. The gene discussed is PAX5; the disease is chronic kidney disease.