title: Antineutrophil cytoplasmic antibody (ANCA) testing of routine sera varies in different laboratories but concordance is greater for cytoplasmic fluorescence (C-ANCA) and myeloperoxidase specificity (MPO-ANCA).
abstract: Most laboratories screen for antineutrophil cytoplasmic antibodies (ANCA) with indirect immunofluorescence (IIF) and confirm cytoplasmic (C-ANCA) and perinuclear (P-ANCA) staining with ELISAs for proteinase 3 (PR3) and myeloperoxidase (MPO) specificities. This study determined the concordance of ANCA test results from 48 diagnostic laboratories participating in a national Quality Assurance programme, that used different assays and methods and varied in expertise. Laboratories were circulated with a questionnaire about their techniques, and provided with 24 sera for testing over a 30 month period. Results for individual sera were compared with the 'observed consensus' found in more than 50% of laboratories. The 23 laboratories (48%) that responded to the questionnaire used 5 different IIF substrates and 11 ELISAs, and differed in other aspects of testing. Concordance for ANCA test results was greater for IIF-positive (n=22, median 96%, range 68%-100%) than an IIF-negative serum (median 64%); for C-ANCA (n=8, median 89%, range 66-100%) rather than P-ANCA (n=10, median 76%, range 52-88%); for MPO-ANCA (n=5, median 100%) rather than PR3-ANCA (n=7, median 89%, range 82-100%); and for strongly-positive (n=2, median 97%, range 96-97%) rather than low positive PR3-ANCA (n=4, median 80%, range 74-86%). Concordance for test results might be improved with further standardisation of testing methodologies.
authors.affiliation: The University of Melbourne, Department of Medicine, The Northern Hospital, Epping VIC 3076, Australia.
authors.forename: Wendy
authors.initials: W
authors.lastname: Pollock
authors.forename: Sue
authors.initials: S
authors.lastname: Jovanovich
authors.forename: Judy
authors.initials: J
authors.lastname: Savige
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D000918:Antibody Specificity; D001315:Australia; D015415:Biomarkers / Q000097:blood; D019411:Clinical Laboratory Techniques / Q000592:standards*; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards*; D019084:Fluorescent Antibody Technique, Indirect / Q000592:standards*; D006801:Humans; D053146:Myeloblastin / Q000276:immunology*; D015588:Observer Variation; D009195:Peroxidase / Q000276:immunology*; D011237:Predictive Value of Tests; D011785:Quality Assurance, Health Care / Q000592:standards*; D011786:Quality Control; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D009195:Peroxidase; D053146:Myeloblastin