Abstract
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.
Highlights
The presence of anti-plasminogen antibodies (α-PLG) in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) received much attention, especially in relation to the nature and severity of renal lesions.[1,2,3] These antibodies inhibit fibrinolysis by disturbing the conversion of plasminogen (PLG) to plasmin.[1,2] A study on patients with AAV showed that patients with α-PLG had significantly more glomerular fibrinoid necrosis accompanied by worse renal function.[2]
We found that 14.3% of MPO-antineutrophil cytoplasmic antibody (ANCA) patients tested had α-PLG, whereas all our PR3-ANCA patients tested negative
Berden et al found α-PLG in approximately 25% of patients with PR3-ANCA and with MPO-AAV
Summary
The presence of anti-plasminogen antibodies (α-PLG) in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) received much attention, especially in relation to the nature and severity of renal lesions.[1,2,3] These antibodies inhibit fibrinolysis by disturbing the conversion of plasminogen (PLG) to plasmin.[1,2] A study on patients with AAV showed that patients with α-PLG had significantly more glomerular fibrinoid necrosis accompanied by worse renal function.[2] the presence of α-PLG in AAV may be an important hallmark for a specific phenotype of the disease.[2,3] Three important studies on α-PLG in AAV reported differences in the proportion of α-PLG positive AAV. November 12, 2018 α-plasminogen antibodies in ANCA-associated vasculitis decision to publish, or preparation of the manuscript. Euro Diagnostica provided support in the form of salaries for authors EG, YS, JW and research materials, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section
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