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Extended report
IgG anti-pentraxin 3 antibodies in systemic lupus erythematosus
  1. N Bassi1,
  2. A Ghirardello1,
  3. M Blank2,
  4. S Zampieri1,
  5. P Sarzi-Puttini3,
  6. A Mantovani4,
  7. Y Shoenfeld2,
  8. A Doria1
  1. 1Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Italy
  2. 2Department of Medicine B, Center for Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, Sackler Faculty of Medicine, Tel-Aviv University, Israel
  3. 3Rheumatology Unit, L Sacco University Hospital, Milan, Italy
  4. 4Institute of Pharmacologic Research ‘Mario Negri’, University of Milano, Milano, Italy
  1. Correspondence to Professor Andrea Doria, Division of Rheumatology, University of Padova, Via Giustiniani, 2, 35128 Padova, Italy; adoria{at}


Objective To evaluate the prevalence and correlates of anti-pentraxin 3 (PTX3) antibodies in systemic lupus erythematosus (SLE).

Methods Serum samples from 130 patients with SLE, 130 age- and sex-matched healthy subjects and 130 patients with other autoimmune rheumatic diseases (oARD) were analysed by home-made ELISAs using as substrate human recombinant PTX3 and two peptides, PTX3_1 and PTX3_2, obtained from the complete protein, identified as potential antigenic sites using the Lasergene DNA program (DNA Star). Inhibition tests were performed to evaluate potential interferences between bovine serum albumin or C-reactive protein and anti-PTX3 or anti-PTX3 peptides, and between antigens and antibodies. Statistical analysis was performed using receiving operating characteristics curves, the Fisher exact test, two-tailed t test and Pearson correlations.

Results Patients with SLE had higher levels and prevalence of anti-PTX3, anti-PTX3_1 and anti-PTX3_2 antibodies than patients with oARD or healthy controls (p<0.001 for all). No differences were observed between patients with oARD and healthy controls. A correlation was found between anti-PTX3 and anti-PTX3_2 antibodies (r=0.615, p<0.001). No association was observed between these antibodies and disease activity. Univariate and multivariate analyses showed that anti-PTX3 and anti-PTX3_2 antibody levels and prevalence were higher in patients without glomerulonephritis and in patients positive for antiphospholipid antibody. All inhibition tests were negative apart from PTX3 against anti-PTX3 antibody or, to a lesser extent, against anti-PTX3_2 antibody, and PTX3_2 against anti-PTX3_2 antibody, all in a dose-dependent manner.

Conclusions Anti-PTX3 antibodies are significantly prevalent in patients with SLE where they might provide protection from renal involvement. The antigenic properties of PTX3_2 peptide are similar to those of PTX3, suggesting its potential use in further analyses.

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  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with the approval of the ethics committee of University-Hospital of Padova.

  • Provenance and peer review Not commissioned; externally peer reviewed.