Diagnostic value of monospecifc DFS70 antibodies in systemic utoimmune rheumatic diseases

Abstract

The detection in serum of monospecifc antibodies that induce a dense fne-speckled fluorescence when interacting with the DFS70 / LEDGF / p75 nuclear antigen is negatively associated with the development of systemic autoimmune rheumatic diseases (SARD) and increases the diagnostic specifcity of the screening study of antinuclear antibodies (ANA) using indirect immunofluorescence on HEp-2 cells (IIF-HEp-2). The results of assessing the clinical signifcance of anti-DFS70 antibodies vary depending on the test systems and the selection of patient groups. The aim of this work is to study the frequency of detection of monospecifc anti-DFS70 antibodies in blood serum in healthy individuals and patients with SARD. Sera of 74 healthy donors and 59 patients with SARD were studied (27 – systemic lupus erythematosus – SLE, 15 – Sjogren's syndrome – SjS, 17 – rheumatoid arthritis – RA). Classical antinuclear antibodies (ANA) and anti-DFS70 antibodies were determined by IIF using a mixture of standard and genetically engineered DFS70-KO HEp-2 cells that do not express DFS70 / LEDGF / p75 as a substrate. 14.9% of healthy donors and 83.1% of SARD patients (96.3% – SLE, 100.0% – SS, 47.1% – RA) were seropositive for antinuclear factor (ANF). Classical ANA with homogeneous, speckled, nucleolar, cytoplasmic, mixed types of fluorescence and the absence of anti-DFS70 antibodies were found in all ANF-positive patients with SARD and in 8.1% of healthy donors. Monospecifc anti-DFS70 antibodies without classical ANA were detected in 6.8% of healthy individuals and were absent in SARS. Among ANF-positive healthy donors, the frequency of isolated detection of anti-DFS70 antibodies was 45.5%. The detection of monospecifc anti-DFS70 antibodies can be considered as a potential predictive marker for excluding the diagnosis of SARD in ANF-positive patients with no or unclear clinical signs of these diseases.