Elevated Levels of Interferon‐α Act Directly on B Cells to Breach Multiple Tolerance Mechanisms Promoting Autoantibody Production.

Objective: Elevated levels of serum interferon‐α (IFNα) and the disruption of B cell tolerance are central to systemic lupus erythematosus (SLE) immunopathogenesis; however, the relationship between these 2 processes remains unclear. The purpose of this study was to investigate the impact of elevated IFNα levels on B cell tolerance mechanisms in vivo and determine whether any changes observed were due to the direct effect of IFNα on B cells. Methods: Two classical mouse models of B cell tolerance were used in conjunction with an adenoviral vector encoding IFNα to mimic the sustained elevations of IFNα seen in SLE. The role of B cell IFNα signaling, T cells, and Myd88 signaling was determined using B cell–specific IFNα receptor–knockout, CD4+ T cell–depleted, or Myd88‐knockout mice, respectively. Flow cytometry, enzyme‐linked immunosorbent assay, real‐time quantitative polymerase chain reaction, and cell cultures were used to study the effects of elevated IFNα on the immunologic phenotype. Results: Elevation of serum IFNα disrupts multiple B cell tolerance mechanisms and leads to autoantibody production. This disruption was dependent upon B cell expression of IFNα receptor. Many of the IFNα‐mediated alterations also required the presence of CD4+ T cells as well as Myd88, suggesting that IFNα acts directly on B cells to modify their response to Myd88 signaling and their ability to interact with T cells. Conclusion: The results provide evidence that elevated IFNα levels act directly on B cells to facilitate autoantibody production and further highlight the importance of IFN signaling as a potential therapeutic target in SLE. [ABSTRACT FROM AUTHOR]