Content area

Full text

Michael Mahler [1] and Chelsea Bentow [1] and Tyler O’Malley [2] and Claudia Ibarra [2] and John Conklin [2] and Mary Ann R. Aure [1] and Thierry Dervieux [2]

Academic Editor: Ethan M. Shevach

1, Inova Diagnostics Inc., San Diego, CA, USA, inovadx.com

2, Exagen Diagnostics, Vista, CA, USA, exagen.com

Received Jul 7, 2017; Accepted Oct 22, 2017

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. Introduction

A variety of assays on many platforms have been developed over the years to detect antibodies to double-stranded (ds) DNA, a key diagnostic marker of systemic lupus erythematosus (SLE). These assays include the Farr assay [1], the Crithidia luciliae indirect immunofluorescence test (CLIFT) [2], and a variety of solid-phase immunoassays [3]. As current solid-phase immunoassays have variable performances due to lack of standardization [3], CLIFT is often regarded as a reference method, owing to its high clinical specificity and the omission of radioactive labeling in contrast to the Farr assay. Recently, a novel assay that uses synthetic DNA has been developed on the BIO-FLASH system, a chemiluminescence immunoassay analyzer, and has been found to demonstrate strong association with disease activity and lupus nephritis [4–6].

Currently, rheumatologists mostly rely on disease activity scores based on organ involvement and clinical parameters. Such scores include the British Isles Lupus Activity Group (BILAG) index, the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), the Systemic Lupus Activity Measure-Revised (SLAM-R), the European Consensus Lupus Activity Measurement (ECLAM), and the Lupus Activity Index (LAI) [7]. All of the abovementioned scores have a subjective component which represents a significant drawback. Consequently, an objective and reliable variable to define disease activity in SLE patients would be of utmost utility in the clinical management of SLE patients. We previously established that clinical improvements in SLE paralleled the reduction in the titers of anti-dsDNA as determined using solid-phase immunoassays [8].

The goal of our study was to evaluate the performance of different assays for the detection of anti-dsDNA antibodies in a well-characterized cohort of SLE patients in a longitudinal study design with special focus on the assessment of disease activity.

2. Methods

2.1. Specimens

The patient...

Show less