A Simple Method to Prepare Anti-Neutrophil Cytoplasmic Antibody Slides

Won, Dong Il

Abstract

BACKGROUND: Neutrophils fixed on a slide are used in indirect immunofluorescence assay (IIF) for anti-neutrophil cytoplasmic antibody (ANCA). A simple method to prepare ANCA slides is described in this report.
METHODS
This method uses an overlay method to separate WBC from EDTA whole blood and Octospottrade mark kits to cytocentrifuge WBC onto 8-well slides. This in-house ANCA IIF was compared with commercial ANCA IIF using 40 sera, and with enzyme linked immunosorbent assay for anti-myeloperoxidase (MPO) antibody (MPO ELISA) using 117 sera.
RESULTS
In ANCA IIF parallel tests using 10 positive and 30 negative sera, in-house slides were in good qualitative agreement, 97.5% (39/40) with commercial kits (kappa=0.93). Fluorescence pattern and intensity of positive reaction was also highly concordant between two methods. In MPO ELISA positive cases, the positivity rate of in-house ANCA IIF was 97.8% (45/46), which accounts for its assay sensitivity for the presence of anti-MPO antibody.
CONCLUSIONS
In-house ANCA slides was convenient and cost-efficient to be prepared. As these slides were found to have acceptable agreement and sensitivity as compared with commercial kits, in-house ANCA IIF is considered to be useful to screen ANCA in combination with MPO ELISA in routine clinical laboratory practice.