Autoreactive long-lived plasma cells (LLPCs) are early and continuously generated in NZB/W mice. Absolute numbers of cyclophosphamide-resistant LLPCs secreting double-stranded DNA (dsDNA)-specific antibody in spleen and bone marrow. NZB/W F1 mice at 4, 6, 8 and 20, 24, 30 weeks of age were treated with four injections of cyclophosphamide (35 mg/kg bw) within two weeks in order to deplete plasmablasts and short-lived plasma cells . After treatment, the remaining anti-dsDNA-specific LLPCs were enumerated by enzyme-linked immunospot (ELISPOT). Data are presented as mean and standard error of the mean (SEM). n = 4-5 mice per time point.