Article

Epitope mapping of antibodies against ferritin heavy chain in giant cell arteritis and polymyalgia rheumatica

Department of Immunology and Rheumatology, Medical University Hannover , Germany.
Scandinavian journal of rheumatology (Impact Factor: 2.53). 05/2013; 42(3):215-219. DOI: 10.3109/03009742.2012.733959
Source: PubMed

ABSTRACT

Objectives:
In a previous study we found an association between antibodies against the human ferritin heavy chain (HFC) protein and giant cell arteritis (GCA) and/or polymyalgia rheumatica (PMR), especially in GCA/PMR patients prior to glucocorticoid treatment. Antibodies against the N-terminal part of ferritin were present in 92% of untreated patients, 69% of patients with disease flare, and 13% of patients in remission. These antibodies appeared to be markers for the early detection of a disease complex usually diagnosed with considerable delay. Our aim in this study was to optimize the diagnostic test by epitope mapping of antibodies against HFC using peptide antigens in enzyme-linked immunosorbent assays (ELISAs).

Method:
We evaluated serum samples from a selected group of GCA/PMR patients in whom the sensitivity of antibodies against the N-terminal ferritin peptide was only 35%. Patients with late-onset rheumatoid arthritis (LORA), patients with fever, patients with granulomatosis with polyangiitis (GPA), patients without any autoimmune disease at age > 65 years, and blood donors served as controls.

Results:
By combining different ELISAs we were able to increase the frequency of human ferritin peptide antibodies in GCA/PMR (p < 0.0001) without significantly altering the false-positive rate (FPR) of the diagnostic test. The frequency of antibodies against human ferritin peptide increased from 53% to 74% in GCA/PMR patients with disease flare, from 29% to 40% in GCA/PMR patients in partial remission, and from 8% to 45% in GCA/PMR patients in complete remission.

Conclusions:
The potential diagnostic test for GCA/PMR can be improved by combining three human ferritin peptide antibodies.

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