PLoS ONE (Jan 2018)

Anti-plasminogen antibodies in ANCA-associated vasculitis: An optimized anti-plasminogen assay.

  • Arda Göçeroğlu,
  • Elsa Grenmyr,
  • Annelies E Berden,
  • E Christiaan Hagen,
  • Donna Bunch,
  • Yngve Sommarin,
  • Jan A Bruijn,
  • Ingeborg M Bajema,
  • Jörgen Wieslander

DOI
https://doi.org/10.1371/journal.pone.0207064
Journal volume & issue
Vol. 13, no. 11
p. e0207064

Abstract

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Anti-plasminogen antibodies (α-PLG) were previously detected in a subpopulation of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients, showing a relation to renal lesions and outcome. Several studies showed different proportions of α-PLG positive AAV patients, possibly due to differences in the assays used. We here present a new, optimized α-PLG Enzyme-Linked Immuno Sorbent Assay (ELISA) and validate the presence of α-PLG in AAV. Different ELISA set-ups were tested regarding plasminogen (PLG) antigen, concentrations, coating buffers, blocking agents, and environmental conditions. Purified lysine-PLG (lys-PLG) showed better differentiation between positive samples and negative samples than glutamic acid-PLG (glu-PLG). Therefore, lys-PLG was used as coating antigen. With the optimized α-PLG ELISA we found α-PLG in 14.3% of the myeloperoxidase (MPO)-ANCA patients, whereas all our proteinase-3 (PR3)-ANCA patients tested in our new assay were negative. Concluding, in this study we have combined important technical findings and methods from previous studies to optimize the α-PLG assay, which can be used for future research purposes and will aid in uniform reporting of α-PLG status of patients.