ANCA disease:
immunoserology and
pathogenesis
Alenka Vizjak
Institute of Pathology · Faculty of Medicine
University of Ljubljana, Ljubljana, Slovenia
Antineutrophil cytoplasmic
antibodies (ANCA)
• Davies DJ et al. Necrotizing glomerulonephritis with ANCA. Med
J 1982; 285:606
• Van der Woude FJ et al. Autoantibodies against neutrophils and
monocytes: Tool for diagnosis and marker of disease activity in
Wegener's granulomatosis. Lancet 1985; 1:425
• Jennette JC et al. ANCA-associated GN and vasculitis. Am J
Pathol 1989; 135: 921
Discovery of ANCA – of key importance for
the classification of small vessel vasculitides
(in the kidney necrotizing crescentic GN)
and understanding of their pathogenesis
(1. immune complex, 2. anti-GBM, 3. ANCA)
ANCA disease
Pathogenetically determined group of smallvessel vasculitides including:
• Wegener’s granulomatosis
• Microscopic polyangiitis
• Pauci-immune necrotizing crescentic GN
= kidney-limited microscopic poliangiitis
• Churg-Strauss syndrome
ANCA antigens
ANCA specific for various proteins, mostly
enzymes, localized in the cytoplasmic
lyzosomes of neutrophils and monocytes.
Major target antigens for ANCA in patients with
pauci-immune small vessel vasculitides :
• Myeloperoxidase (MPO) – epitope expressed
by 130 kDa native molecule in the azurophilic
granules
• Proteinase 3 (PR3) – 28 kDa serine proteinase,
colocalized with MPO in the azurophilic
granules
ANCA antigens
Other ANCA antigens:
lactoferrin, elastase, lysozyme, cathepsin
G, azurocidin, bactericidal permeability
increasing protein (BPI), alpha-enolase,
defensin, unknown
human lysosomal-associated membrane
protein 2 (h-lamp-2) - homologous to
bacterial protein FimH (Kain R et al. Nat
Med 2008)
ANCA testing
• Indirect immunofluorescence (IIF)
C-ANCA ( PR3)
P-ANCA, with nuclear extension ( MPO)
P-ANCA, without nuclear extension
( mostly unknown antigens)
Atypical C-ANCA ( PR3 after treatment or
BPI, MPO, other, often multiple antigens)
Atypical ANCA ( other, often multiple antigens)
• Enzyme-linked immunosorbent assay (ELISA)
Antigen specificity, quantitative value (relative)
Sensitivity and specificity of ANCA (IIF + ELISA for
PR3, MPO) from different studies in the literature
Disease
Sensitivity of ANCA
___________________________________________________
Limited Wegener's granulomatosis
50-66 %
Generalized Wegener's granulomatosis
80-98 %
Microscopic polyangiitis
82-90 %
Pauci-immune necrotizing extracap GN
90-95 %
Churg-Strauss syndrome
60-70 %
Control group
Specificity of ANCA
____________________________________________________
Patients with various other diseases
76-91 %
Healthy subjects
94-99 %
Selected demographic features and serologic
findings in 423 ANCA positive patients grouped
according to their clinico-pathologic settings
(Institute of Pathology, Faculty of Medicine, Ljubljana)
Features
Pauci-immune
vasculitis
(n=153)
Suspected
vasculitis
(n=59)
IBD, AHBD
(n=83)
Other
diseases
(n=128)
59.614.2
60.717.0
40.117.5
53.718.2
93/60
38/21
52/21
80/48
PR3-ANCA
22951.0
51.17.8
24.11.9
33.84.4
MPO-ANCA
570.871.3
65.89.9
31.54.4
34.52.5
Age
Female/male
IBD = inflammatory bowel diseases, AHBD = autoimmune hepato-biliary disorders
Clinico-pathologic diagnosis in relation to ANCA
antigen specificity in 423 ANCA positive patients
(Institute of Pathology, Faculty of Medicine, Ljubljana)
No of
pts
PR3
MPO
PR3+
MPO
Other
ags
56
54
28
45
3
2
6
45
24
2
2
0
3
4
0
Skin vasculitis
2
8
0
1
1
3
0
0
1
4
Goodpasture sy + ANCA
5
0
5
0
0
59
211
12
20
26
76
6
22
15
93
Diagnosis
Wegener’s granulomatosis
Microscopic polyangiitis
Pauci-immune necr GN
Churg-Strauss syndrome
Suspected vasculitis
IBD, AHBD, other diseases
Patogenetic role of ANCA
• Clinical evidence
Correlation between ANCA values and activity of
vasculitis, as well as relapses
Drug-induced ANCA vasculitis
• In vitro studies
Activation of neutrophils by binding of ANCAs 
release of destructive enzymes and toxic reactive oxygen
radicals, as well as neutrophil extracellular traps;
factors released by activated neutrophils activate the
alternative complement pathway;
ANCAs bind also to ANCA antigens adsorbed to anionic
endothelium and GBM, enhancing complement
dependent cytotoxicity;
ANCAs disregulate neutrophil apoptosis  necrosis;
specific T lymphocytes for PR3
• Several animal models of ANCA disease
MPO-ANCA, PR3-ANCA, anti-LAMP-2 antibodies
Falk RJ, Jennette JC. J Am Soc Nephrol 2010, 21: 745-752
De Lind van Wijngaarden RAF et al, Clin JASN, 2008, 3: 237-252
Conclusions
• PR3- and MPO-ANCA are highly specific
diagnostic marker for pauci-immune small
vessel vasculitides determined as ANCA
disease. Rarely, ANCA specific for other
antigens are involved in ANCA disease.
• ANCA can be not rarely positive in various other
diseases, mostly with an atypical IIF pattern, in
low values, and specificities for rare and
unknown ANCA antigens.
• In view of clinical serologic correlations, as well
as in vitro studies and in vivo animal models
ANCA evidently have a key role in the
pathogenesis of glomerular and vascular
lesions in ANCA disease.