Background Primary Sjögren’s syndrome (pSS), a chronic and slowly progressive autoimmune disease, is characterised by lymphocytic infiltration of the exocrine glands characteristically leading to xerostomia and keratoconjunctivitis sicca. Furthermore, the disease can cause severe organ manifestations like interstitial lung disease, cryoglobulinaemic vasculitis, and central or peripheral nervous system-involvement. Moreover, the risk for the development of malignant lymphoma is considerably enhanced. Serum levels of immunoglobulin free light chains (FLC) are known to be increased in some autoimmune diseases[3,4]. In pSS FLC levels are associated with extraglandular disease , whether there are correlations to other parameters of clinical manifestations, quality of life, depressive symptoms, and EULAR scores is yet unknown.
Objectives To investigate the correlation between FLC serum levels and disease activity as measured by EULAR scores, glandular symptoms, depressive symptoms, and quality of life (QoL) in pSS. Moreover, autoantibodies against Ro/SSA and La/SSB were analysed concerning their light chain distribution.
Methods Thirty-one patients with pSS and without history of lymphoma or evidence of paraproteinaemia were included in this prospective cross-sectional study. The assessment of disease activity was implemented by ESSDAI and ESSPRI. Depressive symptoms were documented with the Patient Health Questionnaire (PHQ-9) and QoL with the 12-Item Short Form Health Survey (SF-12). Light chain distribution of autoantibodies against Ro/SSA and La/SSB was analysed by ELISA.
Results We found a correlation between κFLC levels and disease activity as measured by the ESSDAI (r=0.646, p<0.001). κFLC levels correlated with β2-microglobulin concentrations (r=0.613, p<0.001). sIL2-R neither correlated with FLC levels (κ: p=0.500; λ: p=0.692) nor with the ESSDAI (p=0.130). The ESSPRI (p=0.438, p=0.792), PHQ-9 (p=0.233, p=0.183), and physical QoL (p=0.43, p=0.990) did not correlate with κ or λFLC levels.
Conclusions We found a correlation between κFLC levels and disease activity as measured by the ESSDAI (r=0.646, p<0.001). κFLC levels correlated with β2-microglobulin concentrations (r=0.613, p<0.001). sIL2-R neither correlated with FLC levels (κ: p=0.500; λ: p=0.692) nor with the ESSDAI (p=0.130). The ESSPRI (p=0.438, p=0.792), PHQ-9 (p=0.233, p=0.183), and physical QoL (p=0.43, p=0.990) did not correlate with κ or λFLC levels.
Fox RI. Sjögren’s syndrome. Lancet 2005;366:321-31.
Johnsen SJ, Brun JG, Gøransson LG, et al. The risk of non-hodgkin lymphoma in primary sjögren’s syndrome, a population-based study. Arthritis Care Res2012 published on 8 November 2012. doi:10.1002/acr.21887
Sølling K, Sølling J, Rømer FK. Free light chains of immunoglobulins in serum from patients with rheumatoid arthritis, sarcoidosis, chronic infections and pulmonary cancer. Acta Med Scand 1981;209:473-7.
Urban S, Oppermann M, Reucher SW et al. Free light chains (FLC) of immunoglobulies as parameter resembling disease activity in autoimmune rheumatic diseases. Ann Rheum Dis 2004;63(Suppl 1):141.
Gottenberg J, Aucouturier F, Goetz J, et al. Serum immunoglobulin free light chain assessment in rheumatoid arthritis and primary Sjogren’s syndrome. Ann Rheum Dis 2007;66:23-7.
Acknowledgements The authors thank the patients and Stefanie Bartschat, Renate Helfesrieder, Joshua Henne, and Birgit Nettlenbusch for the excellent technical assistance.
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.