Automated interpretation of ANCA patterns - a new approach in the serology of ANCA-associated vasculitisReport as inadecuate

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Arthritis Research and Therapy

, 14:R271

First Online: 14 December 2012Received: 10 July 2012Revised: 22 November 2012Accepted: 11 December 2012


IntroductionIndirect immunofluorescence IIF employing ethanol-fixed neutrophils ethN is still the method of choice for assessing antineutrophil cytoplasmic antibodies ANCA in ANCA-associated vasculitides AAV. However, conventional fluorescence microscopy is subjective and prone to high variability. The objective of this study was to evaluate novel pattern recognition algorithms for the standardized automated interpretation of ANCA patterns.

MethodsSeventy ANCA-positive samples 20 antimyeloperoxidase ANCA, 50 antiproteinase3 ANCA and 100 controls from healthy individuals analyzed on ethN and formalin-fixed neutrophils formN by IIF were used as a -training set- for the development of pattern recognition algorithms. Sera from 342 patients -test set- with AAV and other systemic rheumatic and infectious diseases were tested for ANCA patterns using the novel pattern recognition algorithms and conventional fluorescence microscopy.

ResultsInterpretation software employing pattern recognition algorithms was developed enabling positive-negative discrimination and classification of cytoplasmic ANCA C-ANCA and perinuclear ANCA P-ANCA. Comparison of visual reading of the -test set- samples with automated interpretation revealed Cohen-s kappa κ values of 0.955 on ethN and 0.929 on formN for positive-negative discrimination. Analysis of the -test set- with regard to the discrimination between C-ANCA and P-ANCA patterns showed a high agreement for ethN κ = 0.746 and formN κ = 0.847. There was no significant difference between visual and automated interpretation regarding positive-negative discrimination on ethN and formN, as well as ANCA pattern recognition P > 0.05, respectively.

ConclusionsPattern recognition algorithms can assist in the automated interpretation of ANCA IIF. Automated reading of ethN and formN IIF patterns demonstrated high consistency with visual ANCA assessment.

AbbreviationsANAantinuclear antibody

ANCAantineutrophil cytoplasmic antibody

AAVANCA-associated vasculitides

C-ANCAcytoplasmic antineutrophil cytoplasmic antibody

CIconfidence interval

EGPAeosinophilic granulomatosis with polyangiitis Churg-Strauss Syndrome

ELISAenzyme-linked immunosorbent assay

ethNethanol-fixed neutrophils

formNformalin-fixed neutrophils

GPAgranulomatosis with polyangiitis Wegener-s

IIFindirect immunofluorescence

κCohen-s kappa

MPAmicroscopic polyangiitis


P-ANCAperinuclear antineutrophil cytoplasmic antibody

PR3proteinase 3

RArheumatoid arthritis

SLEsystemic lupus erythematosus.

Electronic supplementary materialThe online version of this article doi:10.1186-ar4119 contains supplementary material, which is available to authorized users.

Dirk Roggenbuck and Elena Csernok contributed equally to this work.

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Author: Ilka Knütter - Rico Hiemann - Therese Brumma - Thomas Büttner - Kai Großmann - Marco Cusini - Francesca Pregnolato - Mar


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