Immunoassay for quantification of antigen-specific IgG fucosylation

Sustic, T.; Coillie, J. van; Larsen, M.D.; Derksen, N.I.L.; Szittner, Z.; Nouta, J.; ... ; Vidarsson, G. (2022)

Article / Letter to editor

Background: Immunoglobulin G (IgG) antibodies serve a crucial immuno-protective function mediated by IgG Fc receptors (Fc gamma R). Absence of fucose on the highly conserved N-linked glycan in the IgG Fc domain strongly enhances IgG binding and activation of myeloid and natural killer (NK) cell Fc gamma Rs. Although afucosylated IgG can provide increased protection (malaria and HIV), it also boosts immunopathologies in alloimmune diseases, COVID-19 and dengue fever. Quantifying IgG fucosylation currently requires sophisticated methods such as liquid chromatography-mass spectrometry (LC-MS) and extensive analytical skills reserved to highly specialized laboratories. Methods: Here, we introduce the Fucose-sensitive Enzyme-linked immunosorbent assay (ELISA) for Antigen-Specific IgG (FEASI), an immunoassay capable of simultaneously quantitating and qualitatively determining IgG responses. FEASI is a two-tier immunoassay; the first assay is used to quantify antigen-specific IgG (IgG ELISA), while the second gives Fc gamma RIIIa binding-dependent readout which is highly sensitive to both the IgG quantity and the IgG Fc fucosylation (Fc gamma R-IgG ELISA). Findings: IgG Fc fucosylation levels, independently determined by LC-MS and FEASI, in COVID-19 responses to the spike (S) antigen, correlated very strongly by simple linear regression (R-2=0.93, p < 0.0001). The FEASI method was then used to quantify IgG levels and fucosylation in COVID-19 convalescent plasma which was independently validated by LC-MS. Interpretation: FEASI can be reliably implemented to measure relative and absolute IgG Fc fucosylation and quantify binding of antigen-specific IgG to Fc gamma R in a high-throughput manner accessible to all diagnostic and research laboratories. Copyright (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

• COVID-19
• Anti-spike IgG
• IgG glycosylation
• Fucosylation

• All authors: Sustic, T.; Coillie, J. van; Larsen, M.D.; Derksen, N.I.L.; Szittner, Z.; Nouta, J.; Wang, W.J.; Damelang, T.; Rebergen, I.; Linty, F.; Visser, R.; Mok, J.Y.; Geerdes, D.M.; Esch, W.J.E. van; Taeye, S.W. de; Gils, M.J. van; Watering, L. van de; Schoot, C.E. van der; Wuhrer, M.; Rispens, T.; Vidarsson, G.
• Date: 2022-07-01
• Journal: EBioMedicine
• Volume: 81
• DOI: doi:10.1016/j.ebiom.2022.104109