B-Cell Cross-Presentation of Autologous Antigen Precipitates Diabetes

  1. Shane T. Grey1
  1. 1Immunology Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
  2. 2Centre of Immunology and Inflammation, School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia
  1. Corresponding author: Shane T. Grey, s.grey{at}garvan.org.au.

Abstract

For autoimmune conditions like type 1 diabetes to progress, self-reactive CD8+ T cells would need to interact with peptide–antigen cross-presented on the surface of antigen-presenting cells in a major histocompatibility complex (MHC) class I-restricted fashion. However, the mechanisms by which autoantigen is cross-presented remain to be identified. In this study, we show cross-presentation of islet-derived autoantigens by B cells. B cells engage self-reactive CD8+ T cells in the pancreatic lymph node, driving their proliferative expansion and differentiation into granzyme B+interferon-γ+lysosomal-associated membrane protein 1+ effector cells. B-cell cross-presentation of insulin required proteolytic cleavage and endosomal localization and was sensitive to inhibitors of protein trafficking. Absent B-cell MHC class I, or B-cell receptor restriction to an irrelevant specificity, blunted the expansion of self-reactive CD8+ T cells, suggesting B-cell antigen capture and presentation are critical in vivo events for CD8 activation. Indeed, the singular loss of B-cell MHC class I subverted the conversion to clinical diabetes in NOD mice, despite the presence of a pool of activated, and B cell–dependent, interleukin-21–expressing Vβ4+CD4+ T cells. Thus, B cells govern the transition from clinically silent insulitis to frank diabetes by cross-presenting autoantigen to self-reactive CD8+ T cells.

  • Received January 2, 2012.
  • Accepted May 9, 2012.

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  1. Diabetes vol. 61 no. 11 2893-2905
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