Autoantibodies associated with RNA are more enriched than anti-dsDNA antibodies in circulating immune complexes in SLE

E. Åhlin*, L. Mathsson, M. L. Eloranta, T. Jonsdottir, I. Gunnarsson, L. Rönnblom, J. Rönnelid

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


To what extent different autoantibodies accumulate in systemic lupus erythematosus (SLE) immune complexes (ICs), and whether such accumulation is associated with disease activity has been investigated. ICs were isolated from SLE sera by both polyethylene glycol (PEG) precipitation and C1q-binding. Autoantibody specificities were determined using a lineblot assay quantified by densitometry. To compare the relative levels of autoantibodies, levels were normalized to the total levels of IgG measured by ELISA in sera and parallel ICs. Samples were investigated both in a cross-sectional design as well as in a paired design with samples obtained during both active and inactive SLE. All investigated autoantibody specificities except anti-dsDNA were enriched in circulating ICs as compared with parallel sera. The group of antibodies against RNA-associated antigens (anti-RNP/Sm, anti-Sm, anti-SSA/Ro60, anti-SSA/Ro52, anti-SSB/La) all exhibited higher median enrichment than the DNA-associated (anti-dsDNA, anti-histones, anti-nucleosomes) or cytoplasmic (anti-ribosomal P) antigens. In particular autoantibodies against RNP/Sm and SSA/Ro52 had the highest degree of enrichment in SLE PEG precipitates. These findings were corroborated by analysis of autoantibody content in C1q-bound ICs. There was no difference in degree of IC accumulation of the investigated autoantibodies during active and inactive SLE. Our findings demonstrate a difference in enrichment between autoantibodies against RNA- and DNA-associated autoantigens in isolated SLE IC, suggesting that the RNA-associated autoantibodies are more prone to form circulating ICs in SLE, in contrast to antibodies against DNA-associated autoantigens such as dsDNA. These finding have implications in understanding mechanisms of differential autoantibody accumulation in target organs in SLE.

Original languageEnglish
Pages (from-to)586-595
Number of pages10
Issue number6
Publication statusPublished - May 2012

Other keywords

  • anti-DNA antibodies
  • anti-SSA/B antibodies
  • Immune complexes
  • Ro52/Ro60
  • Systemic lupus erythematosus


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