Identification of Galectin-3 as an Auto-Antigen in IgG4-Related Disease

Publication date: Available online 29 May 2018
Source:Journal of Allergy and Clinical Immunology
Author(s): Cory A. Perugino, Sultan B. AlSalem, Hamid Mattoo, Emanuel Della-Torre, Vinay Mahajan, Gayathri Ganesh, Hugues Allard-Chamard, Zachary Wallace, Sydney B. Montesi, Johannes Kreuzer, Wilhelm Haas, John H. Stone, Shiv Pillai
BackgroundThe antigenic trigger that drives the expansion of circulating plasmablasts and CD4⁺ cytotoxic T cells (CD4⁺ CTLs) in patients with IgG4-Related Disease (IgG4-RD) is presently unknown.ObjectiveWe sought to sequence Ig genes from single cell clones of dominantly-expanded plasmablasts and generate recombinant human monoclonal antibodies to identify relevant antigens in IgG4-RD using mass spectrometry.MethodsPaired heavy and light chain cDNAs from dominant plasmablast clones were expressed as monoclonal antibodies (mAbs) and used to purify antigens using immunoaffinity chromatography. Affinity-purified antigens were identified by mass spectrometry and validated by ELISA. Plasma levels of the antigen of interest were also determined using ELISAResultsmAbs expressed from the two dominant plasmablast clones of a patient with multi-organ IgG4-RD stained human pancreatic tissue sections. Galectin-3 was identified as the antigen specifically recognized by both mAbs. Anti-galectin-3 autoantibody responses were predominantly of the IgG4 isotype (28% of the IgG4-RD cohort, p = 0.0001) and IgE isotype (11% of IgG4-RD cohort, p = 0.009). No significant responses were seen from the IgG1, IgG2 or IgG3 isotypes. IgG4 anti-galectin-3 autoantibodies correlated with elevated plasma galectin-3 levels (p=0.001), lymphadenopathy (p=0.04), total IgG elevation (p=0.05), and IgG4 elevation (p=0.03).ConclusionAffinity chromatography using patient-derived monoclonal antibodies identifies relevant auto-antigens in IgG4-RD. IgG4 galectin-3 autoantibodies are present in a subset of IgG4-RD patients and correlate with galectin-3 plasma levels. The marked elevations of circulating IgG4 and IgE observed clinically are, at least in part, due to the development of IgG4 and IgE specific autoantibody responses.

Teaser

Using dominantly-expanded plasmablast clones, we have identified IgG4 and IgE anti-galectin-3 autoantibodies in IgG4-RD, which correlate with IgG4 levels, lymphadenopathy and over-expression of galectin-3.


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