The binding of proteinase 3 antineutrophil cytoplasmic antibodies (PR3-ANCA) varies in different ELISAs
- 1Immunology Unit, Division of Laboratory Medicine, Austin Hospital, Heidelberg, Victoria 3084, Australia
- 2University of Melbourne, Department of Medicine, Austin Health/Northern Health, The Northern Hospital, Epping VIC 3076, Australia
- Correspondence to: Professor J Savige University of Melbourne, Department of Medicine, Austin Health/Northern Health, The Northern Hospital, Epping VIC 3076, Australia; jasavigeunimelb.edu.au
- Accepted 28 July 2003
Abstract
Background: The demonstration of proteinase 3 specific antineutrophil cytoplasmic antibodies (PR3-ANCA), and the estimation of antibody values are useful in the diagnosis and management of patients with Wegener’s granulomatosis (WG). However, external quality assessment programmes suggest that PR3-ANCA binding varies in different assays.
Aim: To demonstrate variations in PR3-ANCA binding in different commercial and in house enzyme linked immunosorbent assays (ELISAs).
Method: Binding of a PR3-ANCA standard and 19 sera from patients with WG was compared in eight commercial and in house assays. Binding was expressed in different units depending on the kit.
Results: One commercial assay performed unsatisfactorily. Three commercial kits produced PR3-ANCA binding (70, 102, and 84 U/ml) close to the expected value for the standard (100 U/ml). Serial dilutions of this standard were linear in only one commercial assay and the in house assay. Sera from patients with WG with borderline binding in the in house assay bound in the eight commercial kits at 0–148 kit units; low binding sera ranged from 0 to 273 units; moderately strong sera bound at 7–260 units; and strongly binding sera bound at 13–336 units. In four assays, at least one strongly positive serum bound at levels greater than the provided range.
Conclusions: Levels of antibody binding and units of binding have not been standardised in commercially available PR3-ANCA ELISAs. This may affect the diagnosis and management of patients with WG, in addition to the implementation of international guidelines for treatment.
- antineutrophil cytoplasmic antibodies
- enzyme linked immunosorbent assay
- proteinase 3
- standardisation
- Wegener’s granulomatosis
- ANCA, antineutrophil cytoplasmic antibodies
- ANA, antinuclear antibodies
- C, cytoplasmic
- ELISA, enzyme linked immunosorbent assay
- IIF, indirect immunofluorescence
- MPO, myeloperoxidase
- P, perinuclear
- PBS, phosphate buffered saline
- PR3, proteinase 3
- SSI, Statens Seruminstitut
- T20, Tween 20
