The regulation of anti -double -stranded DNA B cells in healthy and aged mice

The immune system generates a diverse repertoire of B cells that recognize foreign antigens (Ags) to which it is exposed. Inherent in this generation is the production of B cells specific for self-Ags. Early studies defining the mechanism(s) regulating autoreactive B cells come from studies using immunoglobulin (Ig) transgenic (Tg) models to neo-self Ags. Whether these rules applied to B cells with disease-associated specificities, such as double-stranded (ds) DNA, was not clear. The absence of anti-dsDNA Abs from the serum of non-autoimmune individuals suggests that anti-DNA B cells are normally regulated. In this dissertation, the processes by which anti-dsDNA B cells are regulated in healthy environments and what factors contribute to autoantibody production in specific autoimmune settings were examined. Previously it was shown that B cells expressing heavy (H) and light- (L) chain VH3H9/Vκ4 anti-dsDNA B cell Tgs edited away DNA-reactivity by expressing multiple L-chains. To further investigate factors governing the regulation of anti-DNA B cells, mice containing the VH3H9 H-chain only Tg were studied. This Tg pairs with endogenous L-chains to create both anti-DNA and non-DNA B cells. Splenic hybridomas were generated from VH3H9 mice to determine the range of anti-dsDNA B cells that persist in VH3H9 mice and whether the recovered anti-DNA B cells were expressing multiple H- and L-chains (Chapter 3). Additional experiments were designed to determine if anti-dsDNA B cells were also present in the LNs and whether the splenic and LN populations were similarly regulated (Chapter 4). Finally, whether aging alters the established mechanisms of anti-DNA B cell regulation was investigated (Chapter 5). In these studies, it was found that both Igλ1 and Igκ anti-dsDNA B cells persist in VH3H9 mice without expressing multiple endogenous receptors. Igλ1 anti-dsDNA B cells are present in the LN with a distinct phenotype and localization from those in the spleen. Aged mice display a loss of regulation of anti-dsDNA B cells, and specific factors that could contribute to the age-associated loss of tolerance were defined. In the final chapter, the consequences of the persistence of anti-dsDNA B cells and potential mechanisms contributing to their survival and/or rescue are discussed