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AB0439 Contribution of anti-ferritin antibodies to the diagnosis of giant cell arteritis
  1. A. Regent1,2,
  2. K. H. Ly3,4,
  3. A. Blet2,
  4. C. Agard5,
  5. X. Puéchal1,
  6. N. Tamas2,
  7. C. Le-Jeunne6,
  8. E. Vidal3,4,
  9. L. Guillevin1,
  10. L. Mouthon1,2
  1. 1Pôle de Médecine Interne, Centre de Référence pour les vascularites nécrosantes et la sclérodermie systémique, Hôpital Cochin, Assistance Publique Hôpitaux de Paris (AP-HP), Hopial cochin
  2. 2Institut Cochin, INSERM U1016, CNRS UMR 8104, Université Paris Descartes, paris
  3. 3Service de Médecine Interne A, CHU Dupuytren
  4. 4Laboratoire d’immunologie, EA3842, Limoges
  5. 5Service de Médecine Interne, Hôpital hotel Dieu, Nantes
  6. 6Service de Médecine Interne, Hôpital hotel Dieu, paris, France

Abstract

Background The diagnosis of giant cell arteritis (GCA) can only be ascertained by performing temporal artery biopsy (TAB), and there is no validated biomarker valuable for the diagnosis and/or characterization of the prognosis in this condition. Recently, Baerlecken et al. reported on the detection of antibodies directed at the human ferritin heavy chain (FTH1)in 92% of patients with GCA vs 1% of healthy controls.

Objectives We decided to evaluate the diagnostic value of anti-ferritin antibodies in patients undergoing TAB for a suspicion of GCA.

Methods We included 122 consecutive patients suspected of GCA. Blood sampling was performed at the time of TAB. Among these, 40 had biopsy proven GCA (TAB+ GCA), 29 had biopsy-negative GCA (TAB- GCA), 6 had polymyalgia rheumatica (PMR) and another diagnosis that GCA (GCA controls) and/or PMR was retained in 47 patients. Sera from 40 healthy individuals served as negative controls. We investigated for the presence of IgG directed against 19-45 FTH1 amino-acids by using an ELISA test. Correlations between FTH1 antibodies and clinical manifestations were investigated using non parametrical tests.

Results Anti-FTH1 antibodies were identified in 72.5%, 41.3.9%, 31.9% and 2.5% of patients with TAB+ GCA, TAB- GCA, GCA controls and healthy individuals, respectively, with a threshold at the mean of healthy controls + 2 standard deviations (SD). With a threshold at the mean of healthy controls + 3 SD, anti-FTH1 antibodies were identified in 60%, 34.5%, 21.2% and 0% of the patients with TAB+ GCA, TAB- GCA, GCA controls and healthy individuals, respectively.

By grouping TAB+ GCA, TAB- GCA patients with a threshold at 2 SD, the positive and negative predictive value were of 71.9 and 56.9%, respectively. Positive and negative likely ratio were at 1.96 and 0.58, respectively. In addition, in our population, anti-FTH1 antibody titer as measured by OD level correlated significantly with CRP and no correlation was found with aortic and/or visual impairment.

Conclusions We therefore confirm the presence of anti-FTH1 in 72.5% of patients with histologically proven GCA. However, the detection of anti-FTH1 is not contributory to the diagnosis of GCA in a cohort of patients with suspected ACG. The ability to identify a specific sub-group of patients by ELISA should be evaluated by testing a larger cohort of patients with GCA.

References Baerlecken et al. Ann Rheum Dis. 2012 Jun;71(6):943-7.

Disclosure of Interest None Declared

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