The ANCA consensus prescribes screening by indirect immunofluorescence on neutrophils. We evaluated the first automated ANCA-pattern recognition system. C-ANCA and P-ANCA samples were selected from patients with ANCA-associated vasculitis (AAV). Non-AAV controls included sera from healthy controls , sera with possible interfering antibodies , or miscellaneous ANCA reactivity . ANCA slides were analysed by AKLIDES and routine fluorescence microscopy. The C-ANCA pattern was recognized by routine microscopy in 92% and 97% on ethanol- and formalin-fixed slides, respectively. AKLIDES reported C-ANCA in 74% and 95%, respectively. P-ANCA was recognized by routine microscopy on ethanol-fixed neutrophils in 90%, while AKLIDES reported P-ANCA in 80%. Typically, only 65% and 33% of these samples showed the expected C-ANCA on formalin-fixed neutrophils by routine microscopy and AKLIDES, respectively. A C- or P-ANCA pattern was observed on ethanol-fixed neutrophils in 28% and 23% of the controls by routine microscopy and AKLIDES, respectively. Only 5% of the controls revealed C-ANCA on formalin-fixed neutrophils by routine microscopy and AKLIDES. Altogether, automated ANCA-pattern recognition by AKLIDES is promising. Distinction of C- and P-ANCA is good, but sensitivity on ethanol-fixed neutrophils needs improvement. When optimized, pattern recognition software may play an important role in AAV diagnostics. 1. Introduction Detection of antineutrophil cytoplasmic antibodies (ANCAs) is relevant for the diagnosis of the ANCA-associated vasculitides (AAV), including granulomatosis with polyangiitis (GPA, previously referred to as Wegener’s granulomatosis), eosinophilic granulomatosis with polyangiitis (EGPA; previously referred to as the Churg-Straus syndrome), microscopic polyangiitis (MPA), and renal-limited necrotizing crescentic glomerulonephritis (NCGN) [1]. Classification criteria for these diseases have been defined by the American college of rheumatology (ACR) [2] and the Chapel Hill consensus conference [3]. The presence of ANCA, however, is not part of these criteria which are primarily based on clinical manifestations and histopathology as observed in biopsies obtained from the affected tissues. More recently, a novel consensus methodology for the classification of AAV was developed and validated for epidemiological studies [4]. Importantly, the latter classification criteria incorporated the ANCA status of the patient. The current international consensus on ANCA testing prescribes screening by indirect immunofluorescence (IIF) on ethanol-fixed neutrophils
References
[1]
J. W. Cohen Tervaert and J. Damoiseaux, “Antineutrophil cytoplasmic autoantibodies: how are they detected and what is their use for diagnosis, classification and follow-up?” Clinical Reviews in Allergy and Immunology. In press.
[2]
J. F. Fries, G. G. Hunder, D. A. Bloch et al., “The American college of rheumatology 1990 criteria for the classification of vasculitis: summary,” Arthritis and Rheumatism, vol. 33, no. 8, pp. 1135–1136, 1990.
[3]
J. C. Jennette, R. J. Falk, K. Andrassy et al., “Nomenclature of systemic vasculitides: proposal of an international consensus conference,” Arthritis and Rheumatism, vol. 37, no. 2, pp. 187–192, 1994.
[4]
R. Watts, S. Lane, T. Hanslik et al., “Development and validation of a consensus methodology for the classification of the ANCA-associated vasculitides and polyarteritis nodosa for epidemiological studies,” Annals of the Rheumatic Diseases, vol. 66, no. 2, pp. 222–227, 2007.
[5]
J. Savige, D. Gillis, E. Benson et al., “International consensus statement on testing and reporting of antineutrophil cytoplasmic antibodies (ANCA),” American Journal of Clinical Pathology, vol. 111, no. 4, pp. 507–513, 1999.
[6]
H. K. Choi, S. Liu, P. A. Merkel, G. A. Colditz, and J. L. Niles, “Diagnostic performance of antineutrophil cytoplasmic antibody tests for idiopathic vasculitides: metaanalysis with a focus on antimyeloperoxidase antibodies,” Journal of Rheumatology, vol. 28, no. 7, pp. 1584–1590, 2001.
[7]
E. P. Gall, “Immunotesting for diagnosis in rheumatic diseases,” Archives of Internal Medicine, vol. 149, no. 11, pp. 2401–2402, 1989.
[8]
R. Hiemann, T. Büttner, T. Krieger, D. Roggenbuck, U. Sack, and K. Conrad, “Challenges of automated screening and differentiation of non-organ specific autoantibodies on HEp-2 cells,” Autoimmunity Reviews, vol. 9, no. 1, pp. 17–22, 2009.
[9]
J. G. M. C. Damoiseaux, M. C. Slot, M. Vaessen, C. A. Stegeman, P. Van Paassen, and J. W. C. Tervaert, “Evaluation of a new fluorescent-enzyme immuno-assay for diagnosis and follow-up of ANCA-associated vasculitis,” Journal of Clinical Immunology, vol. 25, no. 3, pp. 202–208, 2005.
[10]
M. V. Talor, J. H. Stone, J. Stebbing, J. Barin, N. R. Rose, and C. L. Burek, “Antibodies to selected minor target antigens in patients with anti-neutrophil cytoplasmic antibodies (ANCA),” Clinical and Experimental Immunology, vol. 150, no. 1, pp. 42–48, 2007.
[11]
A. Melegari Bonaguri C, A. Russo, B. Luisita, T. Trenti, and G. Lippi, “A comparative study on the reliability of an automated system for the evaluation of cell-based indirect immunofluorescence,” Autoimmunity Reviews, vol. 11, pp. 713–716, 2012.
[12]
J. G. M. C. Damoiseaux and J. W. Cohen Tervaert, “From ANA to ENA: how to proceed?” Autoimmunity Reviews, vol. 5, no. 1, pp. 10–17, 2006.
[13]
J. Damoiseaux, J. Austen, and J. W. Cohen Tervaert, “ANCA diagnostics in clinical practice: new developments,” in Advances in the Diagnosis and Treatment of Vasculitis, L. M. Amezcua-Guerra, Ed., pp. 3–18, Intech, Rijeka, Croatia, 2012.
[14]
P. Vermeersch, D. Blockmans, and X. Bossuyt, “Use of likelihood ratios can improve the clinical usefulness of enzyme immunoassays for the diagnosis of small-vessel vasculitis,” Clinical Chemistry, vol. 55, no. 10, pp. 1886–1888, 2009.
[15]
R. Birck, W. H. Schmitt, I. A. Kaelsch, and F. J. Van Der Woude, “Serial ANCA determinations for monitoring disease activity in patients with ANCA-associated vasculitis: systematic review,” American Journal of Kidney Diseases, vol. 47, no. 1, pp. 15–23, 2006.
[16]
G. Tomasson, P. C. Grayson, A. D. Mahr, M. LaValley, and P. A. Merkel, “Value of ANCA measurements during remission to predict a relapse of ANCA-associated vasculitis—a meta-analysis,” Rheumatology, vol. 51, pp. 100–109, 2012.
[17]
M. M. Boomsma, J. G. M. C. Damoiseaux, C. A. Stegeman et al., “Image analysis: a novel approach for the quantification of antineutrophil cytoplasmic antibody levels in patients with Wegener's granulomatosis,” Journal of Immunological Methods, vol. 274, no. 1-2, pp. 27–35, 2003.
