Antineutrophil Cytoplasmic Antibodies Testing Research Articles

Improvement of indirect immunofluorescence technique to detect antineutrophil cytoplasmic antibodies and its impact on test positivity rate.

The indirect immunofluorescence (IIF) technique for antineutrophil cytoplasmic antibodies (ANCA) detection is subject to substantial differences across laboratories. This study aimed to assess the impact of improvements in the IIF-ANCA technique on the positivity rate of ANCA tests. A cross-sectional study was performed with serum samples from patients with ANCA-associated vasculitis (AAV), autoimmune hepatitis (AIH), and ulcerative colitis (UC). A paired analysis was performed for IIF-ANCA results using the traditional method and a modified protocol after a series of specific adjustments in the technique based on the protocol of IIF-ANCA test performed at a nation-wide private laboratory in Brazil. ANCA specificity was assessed by ELISA for anti-proteinase 3 (PR3) and anti-myeloperoxidase (MPO) antibodies. Sixty-one patients were evaluated. The positivity rate of IIF-ANCA tests at disease presentation performed at the University reference laboratory was 32.3% in AAV, AIH, and UC patients, whereas the positivity rates of IIF-ANCA and ELISA tests in other laboratories were 75.0 and 72.7%, respectively. After modifications in the IIF-ANCA technique, there was a significant increase in the positivity rate (14.8 vs 34.3%; P=0.0002) and in median titers [1/40 (1/30-1/160) vs 1/80 (1/40-1/80); P=0.0003] in AAV, AIH, and UC patients. UC had the highest increment in positive results from 5.3 to 36.8%. There was poor agreement between MPO- or PR3-ANCA and both IIF-ANCA techniques. In conclusion, modifications in the IIF-ANCA protocol led to a significant improvement in its positivity rate and titers.

An Unusual Cause of Acute Gastroenteritis, Ascites, and Eosinophilia in a 29-Year-Old Woman

An Unusual Cause of Acute Gastroenteritis, Ascites, and Eosinophilia in a 29-Year-Old Woman

Interference of Antinuclear Antibody (ANA) in Indirect Immunofluorescence Assay (IIFA)-Based Perinuclear Antineutrophil Cytoplasmic Antibody (pANCA) Interpretation

Indirect immunofluorescence assay (IIFA) based on antineutrophil cytoplasmic antibody (ANCA) testing is a commonly employed test for diagnosing autoimmune vasculitis. Antinuclear antibody (ANA) can give rise to a false interpretation of perinuclear-ANCA (pANCA) in ethanol-fixed granulocyte substrates. Analytical interference could frequently occur in setups where ethanol-fixed substrates are used alone. Here, we intend to investigate this ANA interference in pANCA interpretation. In this retrospective study, we studied anti-MPO-negative but ANA-positive and pANCA (IIFA based) samples. We also correlated immunoblot results (where data were available) and checked the association between grades of blot positivity (an indicator of the concentration of ANA) and frequency of pANCA interpretation. Data were analyzed by appropriate statistical techniques (Chi-square and kappa statistics). About 19.2% of ANA blot (ENA-blot) positive samples displayed a pANCA positive pattern in the ethanol-fixed substrate, while this positivity in ENA-blot negatives was 6.5%. In positive ANA-IIFA samples, about 14.7% yielded pANCA patterns (on ethanol fixed substrates). Out of this, nuclear homogenous pattern yielding samples gave the highest frequency pANCA, that is, in 31.5% followed by speckled (11.1%), DFS (10.3%), and centromere (6.7%).The association of the nuclear homogenous pattern was statistically significant. ANA-positive results may interfere with the interpretation of pANCA as observed in ANA-IIFA and ENA-blot positive samples. ANA-IIFA patterns like nuclear homogenous may strongly associate this pANCA interpretation. This can help laboratories perform ANCA testing more effectively, ruling out ANA interference in ANCA screening.

Histological evolution of IgG4 related disease

Histological evolution of IgG4 related disease

Clinical Images: Dacryoadenitis in eosinophilic granulomatosis with polyangiitis mimicking immunoglobulin G4-related disease.

The patient, a 26-year-old woman, presented with a 2-week history of acute swelling in both lacrimal glands (A). She had recently developed uncontrolled asthma and nasal polyps. The laboratory test results were notable for an absolute eosinophil count of 5300 cells per μl (reference range 100-400 μl), exceeding 50% of circulating leukocytes. The antineutrophil cytoplasmic antibody test result was negative. Magnetic resonance imaging of the head confirmed swelling of the bilateral lacrimal glands (B, yellow arrowheads) and rhinosinusitis. A biopsy of her lacrimal gland revealed eosinophil-rich necrotizing granulomatous inflammation with vasculitis (C). Her serum immunoglobulin G4 (IgG4) level was slightly elevated (265 mg/dl, normal upper limit is 121 mg/dl), but IgG4 immunostaining of the biopsy specimen did not show a significant finding. A diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA) was made. Treatment with 30 mg of prednisone was initiated, which was gradually tapered without glucocorticoid-sparing agents over 12 months. The swelling of her lacrimal glands resolved, and she was free of symptoms, including asthma and lacrimal gland swelling, at the 12-month follow-up. In summary, EGPA can present with lacrimal gland swelling and mimic IgG4-related Mikulicz disease (1, 2). A histopathological examination of the swollen lacrimal gland is the key to differentiating EGPA from IgG4-related Mikulicz disease in such cases. Disclosureform Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Environmental factors influencing the risk of ANCA-associated vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of diseases characterized by inflammation and destruction of small and medium-sized blood vessels. Clinical disease phenotypes include microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). The incidence of AAV has been on the rise in recent years with advances in ANCA testing. The etiology and pathogenesis of AAV are multifactorial and influenced by both genetic and environmental factors, as well as innate and adaptive immune system responses. Multiple case reports have shown that sustained exposure to silica in an occupational environment resulted in a significantly increased risk of ANCA positivity. A meta-analysis involving six case-control studies showed that silica exposure was positively associated with AAV incidence. Additionally, exposure to air pollutants, such as carbon monoxide (CO), is a risk factor for AAV. AAV has seasonal trends. Studies have shown that various environmental factors stimulate the body to activate neutrophils and expose their own antigens, resulting in the release of proteases and neutrophil extracellular traps, which damage vascular endothelial cells. Additionally, the activation of complement replacement pathways may exacerbate vascular inflammation. However, the role of environmental factors in the etiology of AAV remains unclear and has received little attention. In this review, we summarized the recent literature on the study of environmental factors, such as seasons, air pollution, latitude, silica, and microbial infection, in AAV with the aim of exploring the relationship between environmental factors and AAV and possible mechanisms of action to provide a scientific basis for the prevention and treatment of AAV.

The Role of Sural Nerve Biopsy in the Diagnosis of Vasculitis.

The diagnostic yield of sural nerve biopsy (SNB) in vasculitis is uncertain. Our aim was to document relevant characteristics of patients undergoing SNB in the investigation of vasculitis; determine the diagnostic yield; relate positive biopsy findings to patient demographic, laboratory, and clinical variables; and to calculate the rate of surgical complications. Patients with suspected vasculitis that underwent SNB as part of diagnostic evaluation at academic medical centers in Sweden and the United Kingdom were identified by searching local pathology databases and clinic registers. A structured review of medical case records and pathology reports was conducted. Histological findings were categorized as definite, probable, or no vasculitis in accordance with the 2015 Brighton Collaboration reinterpretation and update of the Peripheral Nerve Society guidelines for vasculitic neuropathy. Definite and probable findings were considered positive for vasculitis. Ninety-one patients that underwent SNB were identified (45% female). Forty (44%) patients showed histological evidence of vasculitis: 14 definite and 26 probable. A concomitant muscle biopsy conducted in 10 patients did not contribute to the diagnostic yield. Positive antineutrophil cytoplasmic antibody test, organ involvement other than the nervous system, and a longer biopsy sample were associated with a positive biopsy. The reported surgical complication rate was 15%. SNB of sufficient length is a useful procedure to confirm a diagnosis of vasculitis.

The Sound of Interconnectivity; The European Vasculitis Society 2022 Report

The first European Vasculitis Society (EUVAS) meeting report was published in 2017. Herein, we report on developments in the past 5 years which were greatly influenced by the pandemic. The adaptability to engage virtually, at this critical time in society, embodies the importance of networks and underscores the role of global collaborations. We outline state-of-the-art webinar topics, updates on developments in the last 5 years, and proposals for agendas going forward. A host of newly reported clinical trials is shaping practice on steroid minimization, maintenance strategies, and the role of newer therapies. To guide longer-term strategies, a longitudinal 10-year study investigating relapse, comorbidity, malignancy, and survival rates is at an advanced stage. Disease assessment studies are refining classification criteria to differentiate forms of vasculitis more fully. A large international validation study on the histologic classification of anti-neutrophil cytoplasmic antibody (ANCA) glomerulonephritis, recruiting new multicenter sites and comparing results with the Kidney Risk Score, has been conducted. Eosinophilic granulomatosis with polyangiitis (EGPA) genomics offers potential pathogenic subset and therapeutic insights. Among biomarkers, ANCA testing is favoring immunoassay as the preferred method for diagnostic evaluation. Consolidated development of European registries is progressing with an integrated framework to analyze large clinical data sets on an unprecedented scale.

Cutaneous manifestations of antineutrophil cytoplasmic antibody-associated vasculitis (AAV): a concise review with emphasis on clinical and histopathologic correlation.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises a group of small vessel vasculitides grouped by commonalities of clinical manifestations and ANCA testing. Skin findings are not uncommon, although there is considerable overlap and many times nonspecificity. In general, patients with skin findings tend to have more significant systemic illness, and skin lesions most often develop simultaneously or following onset of systemic symptoms. There are clinical and pathological clues of help in the differentiation of skin findings in these disorders. Purpura of various forms with leukocytoclastic vasculitis is common to all AAV. Granulomatosis with polyangiitis (GPA) comprises the largest number of patients with an AAV. Upper airway, oral, ear, and facial lesions, with or without granuloma, are more commonly seen in this AAV. Pyoderma gangrenosum-like lesions, including facial location, while not common are most closely associated with GPA. Eosinophilic granulomatosis with polyangiitis (EGPA) as its name implies is more closely associated with eosinophilic, allergic, or asthmatic conditions. Papular lesions of the extensor extremities showing extravascular granulomatous changes are characteristic but not specific for EGPA. Microscopic polyangiitis (MPA) is more closely associated with livedoid skin changes, and vascular inflammation tends to be deeper in the skin than with the other AAV. Extravascular granulomas are not expected. While the skin findings in AAV can be nonspecific and overlapping, combining careful full skin examination with histopathologic study of selected lesions is critical to making the correct diagnosis and in ruling out other similar diseases not ANCA related. The aim of this article is to encourage increased participation by dermatologists and dermatopathologists in the care of these patients.

Clinical analysis of 15 cases with myeloperoxidase antineutrophil cytoplasmic antibody associated hypertrophic pachymeningitis

To study the clinical features of myeloperoxidase(MPO) antineutrophil cytoplasmic antibody (ANCA) associated hypertrophic pachymeningitis (HP). Clinical data of 15 cases diagnosed with MPO-ANCA vasculitis complicated with HP were retrospectively analyzed. Nine cases were males and the other 6 were females, with an average age of (58±8) years. All cases presented with chronic headache. Contrast-enhanced magnetic resonance imaging (MRI) scan showed local or diffused thickening of cerebral and/or spinal dura matter while brain parenchyma were normal. Nine cases developed multiple cranial nerve paralysis, with trigeminal nerve and auditory nerve involved most commonly. The main clinical manifestations were facial pain, hearing loss and tinnitus. Two cases were complicated with hypertrophic spinal pachymeningitis (HSP) and 4 cases were complicated with pulmonary diseases. Positive serum perinuclear pattern ANCA (pANCA) and MPO could be found in all cases, positive serum IgG4 was seen in two patients. erythrocyte sedimentation rate(ESR;25-116 mm/1h) and C-reactive protein (CRP;29.02-146.00 mg/L) were both elevated in 14 cases. Nine cases had elevated intracranial pressure[180-235 mmH2O (1 mmH2O=0.009 8 kPa)] and abnormal protein level (457.6-3710.0 mg/L) in cerebrospinal fluid. Six cases were treated with glucocorticoids (prednisone 20-60 mg/d) and 9 cased with glucocorticoids and immunosuppressants (methotrexate 15 mg/week or cyclophosphamide 100 mg/d po). All patients achieved remission. MPO-ANCA associated HP is a special type of central nervous system involvement in ANCA associated vasculitis (AAV). It rarely involves the lung or kidney. Steroids and immunosuppressive agents are effective. In HP with unknown underlying diseases, it is suggested to screen ANCA and IgG4 tests for AAV or IgG4-related disease.

Interpreting Rheumatology Laboratory Tests

Interpreting Rheumatology Laboratory Tests

Investigation of anti-neutrophil cytoplasmic antibody presence with indirect immunofluorescence and enzyme-linked immunosorbent assay

Anti-neutrophil cytoplasmic antibodies (ANCA) are a family of autoantibodies that react with proteins expressed mainly in cytoplasmic granules of polymorphonuclear neutrophil granulocytes (PMNs). The ANCA test is used to diagnose small vessel vasculitis and to monitor inflammatory activity. ANCA was initially detected using indirect immunofluorescence (IIF), which allowed differentiation of different patterns, such as p-ANCA (perinuclear) and c-ANCA (cytoplasmic). It is now common to detect antibodies by immunochemical assays using purified proteins, such as Enzyme-Linked Immunosorbent Assay (ELISA). In our study, we evaluated ANCA test results studied with IIF and ELISA methods and recorded patient diagnoses in the system. Serum samples of 4524 patients who were thought to have autoimmunity in their etiology were evaluated for ANCA presence. In accordance with the recommendation of the manufacturer (Euroimmun AG, Lübeck, Germany), serum IFA technique was evaluated for the presence of p-ANCA, c-ANCA. ELISA test (Alegria, Orgentec) was used to detect antibodies against MPO and PR3. The number of ANCA IIF positive patients was 525(11.6%). When we look at the distribution of ANCAs, 275(52.5%) formalin sensitive pANCA, 95 (18%) formalin resistant pANCA, 60 formalin sensitive cANCA(11.5%), 95(18%) formalin resistant cANCA. 18 (3.4%) of ANCA IIFA positives had PR3 antigen and 22 (4.1%) had significant antibody elevation against MPO antigen., ANCA IIF positive samples, according to the diagnosis of information registered in the operating system, consist of 424 (80.8%) autoimmune and inflammatory diseases according to disease groups, 36 (6.9%) malignancies, 18 (3.4%) infectious diseases, 47 (8.9%) are other diseases which are not included in these groups. ANCA is a determinant for many diseases, especially vasculitis. ANCA, which we found in a large number of different disease groups, was found to be an indicator that should be used in the diagnosis and follow-up of many autoimmune and inflammatory diseases.

Antineutrophil cytoplasmic antibody positivity and clinical implications in COVID-19.

Aim: To investigate clinical implications of antineutrophil cytoplasmic antibody (ANCA) positivity detected in COVID-19 patients during follow up. Materials and methods: A retrospective survey in a hospital database was carried out to detect COVID-19 patients in which ANCAs had been tested. Clinical, laboratory and imaging data were collected from this hospital database and compared between ANCA-negative and -positive patients. Results: ANCAs were tested in 87 COVID-19 patients. Eight had positivity in at least one ANCA test. COVID-19 symptoms on admission and rate of pulmonary involvement were similar. Acute phase reactant levels were higher in ANCA-positive patients. Rate of mortality was higher in the ANCA-positive group without statistical significance. Conclusion: ANCA positivity detected during COVID-19 in patients without a prior diagnosis of any rheumatic condition may be related with worse outcomes.

Validation of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis as the Cause of End-Stage Renal Disease in the US Renal Data System.

ObjectiveThe objective of this study was to validate the diagnosis of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) as the primary cause of end‐stage renal disease (ESRD) in the US Renal Data System (USRDS).MethodsWe identified patients with ESRD in the Mass General Brigham (MGB) health care system who were enrolled in the USRDS. The health records of those with AAV listed as the primary cause of ESRD in the USRDS were reviewed to confirm the diagnosis and estimate positive predictive value (PPV). Sensitivity was estimated by evaluating the primary cause of ESRD listed in the USRDS for patients with ESRD due to AAV in the MGB AAV cohort.ResultsWe identified 89 MGB patients with ESRD due to AAV in the USRDS. Of these, 85 cases were confirmed to be true cases of AAV (PPV = 94%). Among the patients classified as having AAV, 84 (99%) had an ANCA test, which was predominantly myeloperoxidase/P‐ANCA (47 [55%]); 36 (42%) had a renal biopsy, and all biopsies were supportive of the diagnosis. The majority (81 [90%]) was identified as AAV by International Classification of Diseases Ninth Revision or International Classification of Diseases 10th Revision codes for granulomatosis with polyangiitis (446.4 or M313.1). Of the 77 MGB AAV cohort patients with ESRD who were linked to the USRDS, 41 (53%) had AAV listed as the cause of ESRD; in the remainder, ESRD was attributed to nonspecific nephritis.ConclusionThe diagnosis of AAV as the cause of ESRD in the USRDS has a high PPV; sensitivity was moderate. These findings support the continued use of the USRDS to study ESRD due to AAV.

Pulmonary Amyloidosis with Multiple Cystic Lesions with Central Calcifications

A non-smoker 80-year old woman with a past medical history of inactive and untreated systemic lupus erythematous diagnosed in 1983 and polymyalgia rheumatica treated with prednisone (3 mg once daily) since 2018, was referred to our emergency department because of left-sided chest pain and dyspnoea. She presented no cough, weight loss or fever and there was no history of Sjogren’s syndrome. Complete blood count was unremarkable and no inflammatory syndrome was observed. A chest CT-scan revealed multiple diffuse cystic parenchymal lesions with thin walls and central nodular calcifications in both lungs (Figure 1A). The sputum culture was negative for mycobacterium tuberculosis, legionella pneumophilia, mycoplasma pneumonia, chlamydia pneumonia, coronavirus, echinococcosis and aspergillus. Anti-Nuclear Antibody (ANA) and anti-Ku tests were positive whereas anti-neutrophil cytoplasmic antibody (ANCA) and anti-nucleoprotein tests were negative. The preoperative pulmonary function tests showed a FEV1 of 78% and a DLCO of 73% of the predicted values.

Indications and diagnostic outcome of antineutrophil cytoplasmic antibody testing in hospital medicine: a pattern of over-screening.

Antineutrophil cytoplasmic antibodies (ANCA) serology can aid in the diagnosis and classification of ANCA-associated vasculitides (AAV). However, it is often ordered in patients without clinical manifestations of vasculitis. In this retrospective chart review, we aim to better understand the clinical practices on ANCA testing. We retrospectively reviewed patients' charts for the indications and diagnostic outcomes ofANCA tests. All ANCA tests ordered at two Canadian hospitals (a community hospital and an academic tertiary hospital) between January and December 2016 were included in the study. Descriptive statistics are used. A total of 302 ANCA tests were included. The majority (n = 198, 65.6%) were ordered without an indication for testing. For those patients with at least 1 clinical manifestation of AAV (n = 104), 25% were ANCA positive and 18.3% resulted in a diagnosis of AAV. In comparison, among those without a clinical manifestation of AAV (n = 198), only 1.5% were ANCA positive and none was diagnosed with AAV. All patients diagnosed with AAV had at least 1 indication for ANCA testing. The three most common clinical presentations in patients with a final diagnosis of AAV were glomerulonephritis (81.8%), pulmonary hemorrhage (45.5%), and multiple lung nodules (31.8%). To our knowledge, this is the first study that evaluates patients with both positive and negative ANCA test results in an inpatient setting. We demonstrated a low rate of ANCA positivity and AAV diagnosis in patients without clinical manifestations of AAV. Overall, there is a high rate of ANCA testing without an indication at our academic institution. This over-testing may be curbed by strategies such as a gating policy, culture changes, and clinician education. Key Points • AAV is a clinical-pathological diagnosis, and despite the usefulness of ANCA testing, it does not confirm nor rule out AAV. • ANCA testing for the diagnosis of AAVis generally onlyindicated when there is a clear manifestation of AAV. • Although patients with AAV may occasionally present without classic signs and symptoms, the diagnostic utility of ANCA serology in this setting is low, and testing is more likely to result in a false-positive or false-negative test. • If clinical suspicion remains highdespite negative ANCA testing, clinicians should seek consultation with a rheumatologist.

중이염을 주소로 내원한 ANCA 음성 제한성 육아종증 다발 혈관염 1례

Granulomatosis with polyangiitis(GPA) is a systemic disease that causes granulomatous inflammation and vasculitis to small to medium sized vessels. Although prompt diagnosis is vital for the successful treatment of the disease, it is often misdiagnosed as a simple inflammatory disease in ENT clinic. Anti-neutrophil cytoplasmic antibody(ANCA) tests positive in up to 90% of GPA, and it is a useful diagnostic marker for its strong association with the disease. However, we experienced ANCA-negative limited GPA presenting with intractable otitis media, thereby reporting this case with a brief review of the literature. (J Clinical Otolaryngol 2021;32:59-64)

C3 glomerulonephritis associated with ANCA positivity: a case report

BackgroundC3 glomerulopathy (C3G) is a recent disease classification that is characterized by the presence of glomerular deposits (composed of C3) in the absence of significant amounts of immunoglobulin and comprises dense deposit disease and C3 glomerulonephritis (C3GN). Most C3GN manifests as membranoproliferative, mesangial proliferative glomerulonephritis patterns via light microscopy. Pure membranous nephropathy (MN)-like glomerular lesions are rare manifestations of C3GN. Anti-neutrophil cytoplasmic antibodies (ANCAs) are also seldomly reported to be positive in C3GN. Herein, we report the case of a C3GN patient presenting with an MN-like glomerular pattern with ANCA positivity.Case presentationA 68-year-old woman was admitted to a local hospital with elevated serum creatinine for two weeks. Laboratory tests showed a hemoglobin level of 85 g/L. Urinalysis was positive for 2 + protein and 360 RBCs/HPF. Blood biochemistry analysis revealed the following concentrations: albumin, 30.3 g/L; globulin, 46.2 g/L; blood urea nitrogen, 19.9 mmol/L; and serum creatinine, 234 µmol/L. The serum C3 level was 0.4950 g/L, and the serum C4 level was 0.1050 g/L. The direct Coombs test was positive. Serologic testing for ANCA revealed the presence of p-ANCA (1:10) by indirect immunofluorescence microscopy assay, as well as the presence of PR3 1.2 (normal range < 1) and MPO 3.5 (normal range < 1) by enzyme immunoassay. Renal biopsy sample pathology showed 2/6 cellular crescents and thickened glomerular basement membranes. Immunofluorescence testing revealed only diffuse, finely granular depositions of C3 along the glomerular capillary walls in frozen and paraffin-embedded tissue sections. Electron microscopy demonstrated the presence of subepithelial electron-dense deposits, similar to those that are observed in membranous nephropathy. Corticosteroid and cyclophosphamide were administered, with a subsequent improvement in renal function.ConclusionsWe present the rare case of a patient with MN-like C3GN with ANCA positivity. C3GN with ANCA positivity may be represented by more crescents, severe renal dysfunction and more extrarenal manifestations. More cases are needed to elucidate the clinicopathologic features and optimal treatments of these patients.

Rituximab for refractory necrotizing scleritis and peripheral ulcerative keratitis secondary to antineutrophil cytoplasmic antibody-negative granulomatosis with polyangiitis

A 52-year-old woman was diagnosed with bilateral necrotizing scleritis (NS) and peripheral ulcerative keratitis secondary to the antineutrophil cytoplasmic antibody (ANCA)-negative granulomatosis with polyangiitis (GPA) as evidenced by increased erythrocyte sedimentation rate, bilateral multiple cavitation lung nodules, and persistent microscopic hematuria. Infective workup and autoimmune tests were negative including the ANCA test. She received multiple courses of high dose intravenous methylprednisolone, intravenous cyclophosphamide, and oral methotrexate. Multiple tectonic patching operations were performed. Despite all the treatment, the disease continued to progress. Eventually, few doses of rituximab were given and the disease was stable for at least a year without any reactivation.

ANCA Testing in Clinical Practice: From Implementation to Quality Control and Harmonization.

Analyses for the presence of anti-neutrophil cytoplasmic antibodies (ANCA) are important in the diagnostic work-up of patients with small vessel vasculitis. Since current immuno-assays are predominantly designed for diagnosis of patients with ANCA-associated vasculitis (AAV), implementation in routine clinical practice, internal and external quality control, and harmonization are focused on this particular use. However, ANCA testing may also be relevant for monitoring therapy efficacy and for predicting a clinical relapse in AAV patients, and even for diagnostic purposes in other clinical situations. In the current review, the topics of implementation, quality control, and standardization vs. harmonization are discussed while taking into account the different applications of the ANCA assays in the context of AAV.