The C3dg Fragment of Complement Is Superior to Conventional C3 as a Diagnostic Biomarker in Systemic Lupus Erythematosus

Autor: Anne Troldborg, Lisbeth Jensen, Bent Deleuran, Kristian Stengaard-Pedersen, Steffen Thiel, Jens Christian Jensenius
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Frontiers in Immunology, Vol 9 (2018)
Druh dokumentu: article
ISSN: 1664-3224
DOI: 10.3389/fimmu.2018.00581
Popis: Introduction/objectivesIn 2012, hypocomplementemia was included in the classification criteria of systemic lupus erythematosus (SLE). The suggested measurement of C3 or C4 often reflect disease activity poorly. Our objective was to establish an assay measuring C3dg, which is generated following complement activation, and to evaluate the assay in a cross-sectional SLE cohort.MethodWe included SLE patients (n = 169) and controls (n = 170) and developed a modified C3dg assay where C3dg fragments were separated from the large plasma proteins by polyethylene glycol (PEG), and the supernatant containing the C3dg fragment was used for analysis in an antibody-based sandwich-type assay. Gel permeation chromatography and western blotting were used to establish the optimal conditions for PEG precipitation.Results16% PEG was optimal for separating C3dg from C3 and the larger protein fragments. The assay showed a high degree of stability when using EDTA plasma, and measurements correlated well with commercially available complement activation assays. SLE patients had higher concentrations in plasma of C3dg than controls (p
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