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Anti-PDGFR-α antibodies measured by non-bioactivity assays are not specific for systemic sclerosis
  1. E Balada,
  2. C P Simeón-Aznar,
  3. J Ordi-Ros,
  4. M Rosa-Leyva,
  5. A Selva-O’Callaghan,
  6. J Pardos-Gea,
  7. V Fonollosa-Pla,
  8. M Vilardell-Tarrés
  1. Research Unit in Systemic Autoimmune Diseases, Vall d’Hebron Research Institute, Hospital Vall d’Hebron, Barcelona, Spain
  1. Dr J Ordi-Ros, Research Unit in Systemic Autoimmune Diseases, Vall d’Hebron Research Institute, Hospital Vall d’Hebron, Passeig Vall d’Hebron 119–129, 08035 Barcelona, Spain; jordi{at}vhebron.net

Abstract

Objective: To evaluate the presence of anti-PDGFR-α antibodies by immunological methods in patients with systemic sclerosis (SSc).

Methods: Fifty-eight women diagnosed with SSc and 36 healthy women controls were included. IgG anti-PDGFR-α were measured by ELISA and immunoblot. Associations with clinical and immunological findings were also studied.

Results: Non-significant differences were detected between patients with SSc and controls: median value 0.287 (range 0–2.06) versus median value 0.226 (range 0–2.94), respectively (p = 0.583). No correlation between the presence of anti-PDGFR-α antibodies and clinical and serological features was found. Serum samples from patients with SSc and healthy people who had high titres of anti-PDGFR-α antibodies by ELISA recognised the same band corresponding to PDGFR-α by immunoblot.

Conclusion: Although anti-PDGFR-α antibodies seem to be disease-specific when determined by bioactivity assays, these antibodies are also detected in normal subjects when immunological methods are used. Thus, anti-PDGFR-α antibodies may arise from natural autoantibodies. Possibly, SSc autoantibodies recognise a different epitope on the PDGFR-α molecule which triggers its stimulatory effect when analysed by functional assays. Alternatively, naturally occurring autoantibodies may even become pathogenic after affinity maturation and class switching in genetically susceptible subjects.

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Footnotes

  • Competing interests: None declared.

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