The majority of long-lived plasma cells (LLPCs) are generated by the age of 14 weeks in NZB/W mice. (A) Age-dependent frequencies of bromodeoxyuridine (BrdU)-negative LLPCs of total CD138+ plasma cells and (B) absolute numbers of BrdU-negative LLPC per organ. Mice of 4, 6, 8, 12 and 24, 26, 27 weeks of age were fed BrdU continuously for two weeks and then subjected to BrdU incorporation analysis of splenic and bone marrow plasma cells. n = 4 mice per time point. (C) Absolute numbers of total plasma cells (PCs), BrdU-negative LLPC and BrdU-positive short-lived plasma cells (SLPC) measured by flow cytometry (left) and double-stranded DNA (dsDNA)-specific antibody-secreting cells (ASCs) measured by enzyme-linked immunospot (ELISPOT) (right) in the kidneys of NZB/W mice at different ages. Mice of 6, 14, 20, 26 and 30 weeks of age were fed BrdU continuously for two weeks and then subjected to BrdU incorporation analysis, and anti-dsDNA-specific ELISPOT of kidney plasma cells. n = 4-11 mice per time point. Data are presented as mean and standard error of the mean (SEM ). Numbers and horizontal bars represent P values from statistical comparison between time points by two-tailed unpaired t test.