Identification of connective tissue disease autoantibodies and a novel autoantibody anti-annexin A11 in patients with “idiopathic” interstitial lung disease

Abstract

Autoantibody; Connective tissue disease; Interstitial lung disease

Autoanticuerpo; Enfermedad del tejido conectivo; Enfermedad pulmonar intersticial

Autoanticòs; Malaltia del teixit connectiu; Malaltia pulmonar intersticial

Background Autoantibodies are a hallmark feature of Connective Tissue Diseases (CTD). Their presence in patients with idiopathic interstitial lung disease (ILD) may suggest covert CTD. We aimed to determine the prevalence of CTD autoantibodies in patients diagnosed with idiopathic ILD. Methods 499 patient sera were analysed: 251 idiopathic pulmonary fibrosis (IPF), 206 idiopathic non-specific interstitial pneumonia (iNSIP) and 42 cryptogenic organising pneumonia (COP). Autoantibody status was determined by immunoprecipitation. Results 2.4% of IPF sera had a CTD-autoantibody compared to 10.2% of iNSIP and 7.3% of COP. 45% of autoantibodies were anti-synthetases. A novel autoantibody targeting an unknown 56 kDa protein was found in seven IPF patients (2.8%) and two NSIP (1%) patients. This was characterised as anti-annexin A11. Conclusion Specific guidance on autoantibody testing and interpretation in patients with ILD could improve diagnostic accuracy. Further work is required to determine the clinical significance of anti-annexin A11.

This project was supported by a grant from the Liverpool Interstitial Lung Disease Service Charitable Fund. The UK-BILD study has received funding from Arrowe Park Endowment Funds. Funders had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; nor in the decision to submit the paper for publication. Research profile myositis line immunoassays were donated by Euroimmun.