The following is a summary of “Differences in IgG autoantibody Fab glycosylation across autoimmune diseases,” published in the JUNE 2023 issue of Allergy & Immunology by Koers, et al.

The prevalence of autoantibody Fab glycosylation has been demonstrated to be increased in several autoimmune diseases. For a study, researchers sought to investigate whether elevated Fab glycosylation is a common feature of autoimmunity by examining the levels of Fab glycosylation on serum IgG and its subclasses for autoantibodies associated with various B cell-mediated autoimmune diseases, including rheumatoid arthritis, myasthenia gravis subtypes, pemphigus vulgaris, antineutrophil cytoplasmic antibody-associated vasculitis, systemic lupus erythematosus, anti-glomerular basement membrane glomerulonephritis, thrombotic thrombocytopenic purpura, and Guillain-Barré syndrome.

They assessed the level of Fab glycosylated IgG antibodies using lectin affinity chromatography and autoantigen-specific immunoassays. In 6 out of 10 autoantibody responses and five out of eight diseases, they observed increased levels of Fab glycosylation on IgG autoantibodies, ranging from 86% in rheumatoid arthritis to 26% in systemic lupus erythematosus. Interestingly, elevated autoantibody Fab glycosylation was not limited to IgG₄, which is known to be prone to Fab glycosylation, but was also present in IgG₁. Moreover, the increased Fab glycosylation was mainly observed in chronic autoimmune diseases rather than acute ones. The study also evaluated Fab glycosylation levels on antibodies to common latent herpes viruses and glycoprotein 120 in individuals with chronic HIV-1 infection but found no association with increased Fab glycosylation, indicating that chronic antigen stimulation alone does not lead to elevated Fab glycosylation levels.

The data suggested that disease-specific autoantibodies are enriched for Fab glycans in chronic but not acute, B cell-mediated autoimmune diseases.

Source: jacionline.org/article/S0091-6749(23)00091-X/fulltext