title: Testing on formalin-fixed neutrophils is less sensitive and specific for small vessel vasculitis, and less sensitive for MPO-ANCA, than most ELISAs.
abstract: This study evaluated the usefulness of testing sera with perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) on formalin-fixed neutrophils to differentiate between vasculitis and other diseases, and to distinguish between myeloperoxidase (MPO) and other antigen targets. Sera from active (n=24) or treated vasculitis (n=23) and non-vasculitic disease (n=37) were tested in 3 ethanol- and 2 formalin-fixed neutrophil assays, and in 12 MPO-ANCA ELISAs. The sensitivity of demonstrating that P-ANCA became cytoplasmic on formalin-fixed cells in vasculitis, and negative in non-vasculitic disease was 75-79% in different assays compared with 88% for positivity in the majority of MPO-ANCA ELISAs. The sensitivity and specificity of demonstrating that P-ANCA became cytoplasmic where the target was MPO, and disappeared with other antigens were 89% and 74-80% respectively in different assays. P-ANCA specificity for MPO should be confirmed in one of the better-performing MPO-ANCA ELISAs.
authors.affiliation: Gribbles Pathology, Melbourne, VIC, Australia.
authors.forename: Wendy
authors.initials: W
authors.lastname: Pollock
authors.forename: Michelle
authors.initials: M
authors.lastname: Trevisin
authors.forename: Judy
authors.initials: J
authors.lastname: Savige
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic / Q000737:chemistry* / Q000276:immunology; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D000431:Ethanol / Q000737:chemistry; D005260:Female; D005404:Fixatives / Q000737:chemistry*; D005557:Formaldehyde / Q000737:chemistry*; D006801:Humans; D008297:Male; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology*; D009195:Peroxidase / Q000276:immunology*; D012680:Sensitivity and Specificity; D016707:Tissue Fixation; D014657:Vasculitis / Q000175:diagnosis* / Q000201:enzymology / Q000276:immunology*
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D005404:Fixatives; D005557:Formaldehyde; D000431:Ethanol; D009195:Peroxidase