Phenotyping of B cells in IgG1-3 and IgG4-mediated autoimmune disease according to Euroflow standards

Immunophenotyping of B cells in peripheral blood mononuclear cells obtained from IgG1-3 (acetylcholine receptor myasthenia gravis, lambert-eaton myasthenic syndrom) and IgG4-mediated autoimmune patients (muscle-specific kinase myasthenia gravis, pemphigus, lgi1 and casrp2 autoimmune encephalitis). The goal of this study was to investigate whether autoantibody subclass predominance is driven by aberrant class switching or alterations in B cell development.
Conclusion:
Relative abundance of B cell subsets was normal at all maturation stages when comparing autoimmune patients to healthy donors. We did not find overrepresentation of B cells or plasma cells with IgG subclass matching the dominant autoantibody subclass. In IgG4 patients, we observed a isotype and subclass-independent increase in circulating mature (CD20-CD138+) plasma cells. Follow-up experiments did not reveal autoreactivity within this subset. In conclusion, B cell development is normal in the autoimmune diseases investigated in this study, suggesting autoantibody subclass predominance is likely antigen-driven. The similarities between B cell subset numbers among patients suggest that IgG4 autoimmune diseases, despite variable clinical phenotypes, share a common underlying immune profile.
Notes:
Preprint available on BioRXiv (https://doi.org/10.1101/2023.06.30.546522) Experiments were performed according to Euroflow standards (https://euroflow.org/) and can be expanded upon with future experiments adhering to the same standards. The EuroFlow 12-color IgH-isotype B-cell tube was used with the exception of CD62L which was replaced by a Zombie Yellow cell viability stain to control for cell viability following a freeze/thaw cycle.