Background Anti-Sa antibodies belong to the group of autoantibodies against citrullinated proteins and peptides (ACPAs) and are found in patients with rheumatoid arthritis (RA).
Objectives The aim of this study was to determine whether a correlation between the disease activity estimated by DAS-28 (disease activity score measured on 28 joints) and the antibody titer of the anti-Sa antibody exists.
Methods In this retrospective study, out of 202 anti-CCP positive patients 36 anti-Sa antibody positive patients could be evaluated who had clinical examinations over a time span of 1 to 3 years. According to disease activity measured by DAS-28 in intervals of 6±2 months the disease courses of the patients were assigned to one of three groups: decreasing DAS-28 (n=25), stable DAS-28 (n=17), increasing DAS-28 (n=11). Within each group anti-Sa antibody concentrations between different time points of 6-months’ time span were compared by Wilcoxon-signed rank test. Anti Sa-antibody was determined in serum samples which were kept frozen at -20 °C until analysis. Concentration of anti-Sa antibodies was measured using a commercially available ELISA (EUROIMMUN, Lübeck, Germany) according to the instructions of the manufacturer.
Results The Wilcoxon signed-rank test showed no significant difference in anti-Sa titers between different time points neither in the group of patients with ongoing improvement of disease activity, stable disease or treatment failures with increasing disease activity. Only in the group of patients with decreasing DAS-28 after 6 and 12 months a significant difference could be seen in the optical density of substrate development (p=0,020 and p=0,005).
Conclusions Only in single cases a correlation was seen between disease activity and anti-Sa antibody titer. Our study indicates that anti-Sa antibody titer seems not to be a marker for disease activity in RA
Disclosure of Interest None Declared
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.