Clinical applications of antineutrophil cytoplasmic antibody testing

PURPOSE OF REVIEW: Antineutrophil cytoplasmic antibodies are closely associated with Wegener granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome and have contributed to new pathogenetic concepts and improved nomenclature of systemic vasculitides (antineutrophil cytoplasmic antibody-associated vasculitides). However, the application of antineutrophil cytoplasmic antibody testing as a clinical diagnostic tool is still regarded as controversial. This review summarizes the most recent developments in the field, identifies areas of uncertainty, and gives practical guidelines. RECENT FINDINGS: The problems of antineutrophil cytoplasmic antibody testing include the diversity of antineutrophil cytoplasmic antibody target antigens, assay standardization and performance, the application of antineutrophil cytoplasmic antibody testing in a clinical setting with a low pretest probability, and, finally, the widespread assumption that antineutrophil cytoplasmic antibody titers alone may closely reflect disease activity and therefore may be used to guide therapy. SUMMARY: Recent findings demonstrate that the combined use of indirect immunofluorescence tests and solid phase assays to detect antineutrophil cytoplasmic antibody directed against myeloperoxidase and proteinase 3 can minimize the occurrence of false-positive antineutrophil cytoplasmic antibody results. Furthermore, the yield of antineutrophil cytoplasmic antibody testing can be improved by the use of a well-standardized test, adherence to published guidelines, and restricting the use of the tests to clinical situations with a rather high pretest probability for antineutrophil cytoplasmic antibody-associated vasculitides. However, treatment decisions should be based on the clinical presentation of the patient and histologic findings and not on the results of antineutrophil cytoplasmic antibody testing alone.     

Bronchiectasis with myeloperoxidase antineutrophil cytoplasmic antibody and bactericidal/permeability-increasing protein antineutrophil cytoplasmic antibody.

A 56-year-old woman was hospitalized for recurrent hemoptysis. She had been suffering from bronchiectasis for 4 years. Pseudomonas aeruginosa was persistently detected in her sputum. Serum was positive for Myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) and bactericidal/permeability-increasing protein antineutrophil cytoplasmic antibody (BPI-ANCA). She underwent lung resection. Histopathologically, the resected lung showed bronchiectasis with pulmonary fibrosis but did not show vasculitis. Her serum became negative for the ANCAs after the operation. To date, she has no recurrence of hemoptysis. We discuss this case of bronchiectasis with MPO-ANCA and BPI-ANCA and suggest a possible role for ANCAs in chronic airway infection.     

Characteristics and outcome of crescentic glomerulonephritis in patients with both antineutrophil cytoplasmic antibody and anti-glomerular basement membrane antibody

A subset of patients with crescentic glomerulonephritis (CGN) is characterized serologically by the presence of antineutrophil cytoplasmic antibody (ANCA) and anti-glomerular basement membrane antibody (anti-GBM) called “double positive” disease. The clinical significance of the occurrence of both antibodies is not clear. This study aims to describe the clinical and histologic characteristics and outcomes of CGN in a US cohort of double positive (DP) patients and compare them to patients with anti-GBM disease only or ANCA only (ANCA-associated vasculitis (AAV)). Renal biopsies with a diagnosis of CGN with either pauci-immune or linear immunofluorescence were selected and classified as AAV, anti-GBM disease, or DP based on serologic testing at the time of biopsy. Data on demographics, clinical presentation, treatment, and outcome were obtained by chart review. Six patients with anti-GBM disease, 9 with DP disease, and 18 AAV patients matched for year of diagnosis with DP were identified. Extrarenal disease manifestations were more prominent in the DP patients. The DP patients had severe renal dysfunction at presentation with eight of nine patients requiring dialysis at presentation. Renal biopsy findings of DP patients were similar to anti-GBM disease with majority of glomeruli showing cellular crescents. Eighty-nine percent of patients were treated with immunosuppressive therapy and 78 % with plasmapheresis. At 1 year, all nine DP patients reached end-stage renal disease. We conclude that the DP patients share extrarenal manifestations similar to AAV patients while the renal manifestations resemble anti-GBM patients clinically and histologically. The renal prognosis of DP patients remains poor despite treatment.     

False positive antineutrophil cytoplasmic antibody in a patient with infective endocarditis

We report a gentleman suffering from purpuric skin rash mimicking vasculitis associated with impaired renal function. He was found to have positive cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) in the serum, but the test for anti-proteinase 3 antibodies (PR3-ANCA) was negative. Blood culture and echocardiogram confirmed the diagnosis of Streptococcal Oralis infective endocarditis. The renal biopsy did not show any features of vasculitis or crescentic glomerulonephritis. His skin rash subsided and renal function normalized after treatment of the infective endocarditis with appropriate antibiotics. Therefore, we conclude that for those patients presenting with features of vasculitis and a positive ANCA test, other causes, such as infective endocarditis, should be considered.     

抗中性粒细胞胞浆抗体对溃疡性结肠炎的诊断价值

目的　探讨抗中性粒细胞胞浆抗体 (ANCA)对溃疡性结肠炎 (UC)的诊断价值。方法　应用间接免疫荧光法 (IIF)、酶联免疫吸附法 (ELISA)和免疫印迹法 (Westernblot)分别对UC患者 ( 5 8例 )、非UC患者 ( 4 3例 )及健康献血员 ( 5 8例 )进行血清ANCA检测。结果　ANCA对UC诊断的敏感性为 3 7.93 % ,特异性为 10 0 %。UC患者中依据病情分为轻、中、重度组 ,ANCA的阳性率分别为17 65 %、4 1.67%和 5 2 .94 %。ANCA阳性肠黏膜炎症III～V级者占 78 95 % ,黏膜血管炎发生率为78 95 % ,而ANCA阴性者分别为 3 7.0 4 %和 4 4.4 4%。髓过氧化物酶 (MPO)、杀菌 /通透性增强蛋白(BPI)、乳铁蛋白 (LF)、组织蛋白酶G(CG)、蛋白酶 3 (PR 3 ) 5种ANCA抗原与UC患者血清的结合率分别为 13 .79%、13 .79%、10 .3 4%、10 .3 4%和 8.62 %。采用Westernblot法对UC患者血清进行检测 ,发现显示特异蛋白条带者占 4 8.2 8% ,其中显示分子量为 4 70 0 0条带者最多 ,占 2 2 .4 1%。结论　ANCA检测可作为UC的辅助诊断手段。目前 ,UC相关ANCA的靶抗原仍未明确 ,研究发现 4 70 0 0蛋白可能是UC相关ANCA的靶抗原之一。ANCA可能参与UC的致病机制。     

抗中笥粒细胞胞浆抗体对溃疡性结肠炎的诊断价值

目的 探讨抗中性粒细胞胞浆抗体（ＡＮＣＡ）对溃疡性结肠炎（ＵＣ）的诊断价值。方法 应用间接免疫荧光法（ＩＩＦ）、酶联免疫吸附法（ＥＬＩＳＡ）和免疫印法（Ｗｅｓｔｅｍ ｂｌｏｔ）分别对ＵＣ患者（５８例）、非ＵＣ患者患者（４３例）及健康献血员（５８例）进行血清ＡＮＣＡ检测。结果 ＡＮＣＡ对ＵＣ诊断的敏感性为３７．９３％,特异性为１００％。ＵＣ患者中依据病情分为轻、中、重度组,ＡＮＣＡ的阳性率分别为１７     

Alternating antineutrophil cytoplasmic antibody specificity: drug-induced vasculitis in a patient with Wegener's granulomatosis

We describe a patient who presented with Wegener's granulomatosis associated with antineutrophil cytoplasmic antibodies (ANCA) directed against proteinase 3 (PR3) with a cytoplasmic immunofluorescence pattern (cANCA), whose ANCA type changed to antimyeloperoxidase antibodies with a perinuclear immunofluorescence pattern (pANCA) when treated with propylthiouracil, and changed back to anti-PR3 antibodies with cANCA after the medication was discontinued. The patient developed flares of vasculitis symptoms associated with rises in either type of ANCA. Tests for antimyeloperoxidase ANCA were repeatedly negative before the drug was started, strongly implicating the drug as the cause of the episode. This case demonstrates that patients with idiopathic ANCA-positive vasculitis may quickly develop a superimposed drug-associated ANCA-positive vasculitis. Iatrogenic vasculitis should be suspected when a patient with idiopathic vasculitis with one type of ANCA develops the other type of ANCA.     

Anti-neutrophil cytoplasmic antibody (ANCA)-associated scleritis: A diagnostic challenge and outcome

Aim of the workThis report aims to present the clinical challenge in managing a case of anterior scleritis associated with anti-neutrophil cytoplasmic antibody (ANCA), which was masquerading as recurrent conjunctivitis and the lines of management and disease course.Case reportA 68-year-old Malaysian male presented with bilateral blurring of vision associated with pain and redness for one-week duration. He had prior episodes of eye redness and discomfort, which was temporarily relieved with a course of corticosteroid eye drops, on presumptive diagnosis of conjunctivitis. Visual acuity was 6/18 bilaterally. Anterior segment examination showed diffuse conjunctival and episcleral injection which was tender on palpation. There was no posterior segment involvement in both eyes. Patient was tested positive for ANCA and proteinase 3 (PR3). Urinalysis showed proteinuria and hematuria. Chest X-ray was clear with no evidence of pulmonary infiltrations, nodules, cavitation or pleural effusion. Electrocardiogram showed left ventricular hypertrophy with right bundle branch block. The patient also had sensorineural hearing loss. A diagnosis of ANCA-associated scleritis was made and patient was treated with a combination of oral glucocorticoids and azathioprine. The patient had two episodes of anterior scleritis and developed bilateral peripheral ulcerative keratitis (PUK) which resulted in permanent visual impairment with no further progress. Ongoing rheumatology service work-up for systemic vasculitis could not classify the case.ConclusionANCA-associated vasculitis can have atypical ocular presentation and can be clinically misdiagnosed as conjunctivitis. Long term visual and systemic complications can be prevented with early detection and prompt immunosuppressive treatment.     

Detection of antineutrophil cytoplasmic antibody in a patient with L-tryptophan induced eosinophilia-myalgia syndrome.

The Center for Disease Control has received numerous reports of an eosinophilia-myalgia syndrome related to products containing L-tryptophan. The case is reported of eosinophilia-myalgia syndrome and polyneuropathy associated with myeloperoxidase specific antineutrophil cytoplasmic antibody.     

Perinuclear antineutrophil cytoplasmic antibody myeloperoxidase-positive vasculitis in association with ulcerative colitis

We describe a patient with ulcerative colitis (UC) who developed small vessel vasculitis. Perinuclear antineutrophil cytoplasmic antibody myeloperoxidase (p-ANCA-MPO) positivity was detected along with a highly elevated titer of anticardiolipin antibodies. A total proctocolectomy was undertaken and the patient, more than 5 years later, remains in very good condition. The possible causative association between the UC, the p-ANCA-MPO-positive small vessel vasculitis, and the anticardiolipin antibodies is discussed.     

Frequency of antineutrophil cytoplasmic antibody in Graves' disease patients treated with methimazole

Retrospective studies have shown antineutrophil cytoplasmic antibody (ANCA) positivity in patients treated for Graves' hyperthyroidism; ANCA has been attributed to either antithyroid drugs or to the disease itself. The aim of this study was to determine ANCA in Graves' disease patients at diagnosis and after treatment with methimazole and to evaluate the relationship between ANCA and hyperthyroidism evolution. Thirty patients recently diagnosed with Graves' hyperthyroidism were prospectively studied. ANCA were determined by indirect immunofluorescence. ANCA autoantibodies against specific antigens (proteinase 3, myeloperoxidase, bactericidal/permeability-increasing protein (BPI), cathepsin, lysozyme, elastase, and lactoferrin) were detected by ELISA. The median observation period was 22 months. Kaplan-Meier analysis was performed to identify ANCA as an outcome variable. Twenty patients (67%) were ANCA positive before the onset of treatment, and four (19%) remained positive after 1 yr of antithyroid drug treatment. No differences were observed in any clinical or analytical features between patients with or without positive ANCA. Before treatment, BPI-positive patients required radioiodine treatment or presented relapse more rapidly than BPI-negative patients (log-rank test P < 0.0002). Patients with Graves' hyperthyroidism show positive ANCA before medical treatment, which points to a relationship with the autoimmune disease itself. Our results suggest that BPI-positive patients tend to relapse with antithyroid medication.     

Prediction of relapses in Wegener's granulomatosis by measurement of antineutrophil cytoplasmic antibody levels: a prospective study

OBJECTIVE: Prediction of relapses in Wegener's granulomatosis (WG) by measuring levels of antineutrophil cytoplasmic antibodies (ANCA) directed against proteinase 3 (PR3) or myeloperoxidase (MPO) remains a controversial issue. To assess the value of serial quantification of ANCA by indirect immunofluorescence (IIF) and antigen-specific enzyme-linked immunosorbent assay (ELISA) for monitoring disease activity in patients with WG, a prospective observational study was conducted in patients with WG attending an outpatient clinic in the Netherlands. METHODS: One hundred patients with WG (85 with PR3-ANCA, 15 with MPO-ANCA) were studied prospectively from 1996 to 1998. Serum samples were obtained and analyzed every 2 months for ANCA levels. Disease activity was prospectively assessed without knowledge of the ANCA levels. RESULTS: Relapses occurred in 37 of 100 patients (37%). Thirty-four (92%) of the 37 patients showed a rise in the level of ANCA preceding their relapse, as detected by ELISA or IIF. The predictive value of an increase in ANCA titers for relapse was 57% (17 of 30) for cytoplasmic/classic ANCA (cANCA; by IIF), 71% (27 of 38) for PR3-ANCA (by ELISA), and 100% (3 of 3) for MPO-ANCA (by ELISA). The predictive value of a rise in ANCA as measured by ELISA or IIF did not substantially improve following concomitant measurement of the IgG3 subclass of PR3-ANCA. Forty-three percent of patients who showed a rise in cANCA (by IIF) and 29% with a rise in PR3-ANCA (by ELISA) did not subsequently experience a relapse. CONCLUSION: Serial measurement of ANCA levels is valuable for the early prediction of relapses in patients with WG.     

Diagnostic dilemma of antineutrophil cytoplasmic antibody seropositivity in human immunodeficiency virus infection

We present a case of a 48-year-old male who was diagnosed and treated for Wegener's granulomatosis on the basis of history, clinical features, computed tomography (CT) and antineutrophil cytoplasmic antibodies (ANCA) positivity. The patient initially improved and later on during course of the disease he was found to be human immunodeficiency virus (HIV) seropositive. The potential pitfalls of cANCA in a HIV-infected patient are discussed.     

New aspects of antineutrophil cytoplasmic antibody (ANCA) diagnosis in vasculitis

Anti-Neutrophil Cytoplasmic Antibodies (ANCA) are a heterogenous group of autoantibodies with a broad spectrum of clinically associated diseases. The diagnostic value is established of Proteinase 3 (PR3)-ANCA for Wegener's granulomatosis (WG) as well as Myeloperoxidase (MPO)-ANCA for microscopic polyangiitis (MPA). Within the last 20 years these antibodies were subject of intensive studies and a growing body of evidence arose for a distinct role of ANCA in the pathogenesis of the ANCA associated vasculitides WG and MPA. Our current concept of whether ANCA directly or indirectly contribute to vascular damage (ANCA-Cytokine-Sequence-Theory) was mainly developed from in vitro studies. It is plausible and it is supported by data from clinical investigations as well as animal models. Nevertheless our knowledge of the etiological and pathogenetic pathways remains incomplete.     

Autoantibodies and target antigens in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides

In this study of antineutrophil cytoplasmic antibody (ANCA)-associated diseases, we determined the prevalence of other autoantibodies and the antigen specificities of ANCA. ANA were common, occurring in 7 of 36 (19%) patients with Wegener's granulomatosis, in 16 of 34 (47%) patients with microscopic polyarteritis, in 6 of 11 (55%) patients with segmental necrotising glomerulonephritis and in 8 of 18 (44%) of those with ANCA-associated systemic vasculitis without renal involvement. ANA were associated more often with pANCA and microscopic polyarteritis than with cANCA (P<0.05). Patterns were speckled (n=23), homogeneous (n=10) or nucleolar (n=4). Anticardiolipin antibodies were also common, occurring in 10 of 25 (40%) patients with Wegener's granulomatosis, in 8 of 14 (57%) patients with microscopic polyarteritis and in 6 of 18 (33%) of those with a systemic vasculitis. However, anticardiolipin antibodies did not correlate with the presence of ANCA in any of the disease groups. Anti-GBM antibodies were demonstrated in only 2 of 25 (8%) patients with Wegener's granulomatosis, in I patient with microscopic polyarteritis (1/14, 7%) and in 1 with segmental nectrotising glomerulonephritis (1/11, 9%). All four patients with anti-GBM antibodies had either cANCA or pANCA. In the second part of the study, the target antigens of ANCA were determined in Wegener's granulomatosis, microscopic polyarteritis, systemic vasculids, inflammatory bowel disease, rheumatoid arthritis and systemic lupus erythematosus (SLE). Of the 19 sera with cANCA, 13 (68%) were directed against proteinase 3; other antigens were myeloperoxidase (1/19,5%), elastase and lactoferrin together (1/19, 5%), lysozyme (1/19, 5%) or unknown (3/19,16%). Of the 12 (58%) sera from patients with Wegener's granulomatosis who had cANCA, 7 bound to proteinase 3. Antimyeloperoxidase antibodies were present in 14 of 45 (31%) sera with pANCA; other antigens were proteinase 3 (5/45,11 %), elastase (3/45, 78%), lactoferrin (1/45, 2%), cathepsin G (5/45, 11 %) or unknown (17/45, 38%). Antimyeloperoxidase antibodies were common in microscopic polyarteritis (6/14, 43%) and systemic vasculitis (5/16, 31%). However, the majority of target antigens in systemic vasculitis and rheumatoid arthritis with pANCA were not determined. Atypical ANCA were present in four patients, one with inflammatory bowel disease (1/8, 13%) and three with SLE (3/15, 20%). The specificities were cathepsin G, cathepsin G plus lactoferrin, or unknown in two sera. A recent report has suggested that bactericidal /permeability-increasing protein may be the target in patients with inflammatory bowel disease.     

老年人抗中性粒细胞胞浆抗体相关小血管炎肾损害

原发性小血管炎是指一组病因不明、以血管壁炎症和纤维素样坏死为病理特征的系统性疾病,部分与抗中性粒细胞胞浆抗体(ANCA)密切相关,称之为ANCA相关小血管炎(AAV),包括韦格纳肉芽肿病(WG)、显微镜下型多血管炎(MPA)、变应性肉芽肿性血管炎和肾脏局限型血管炎.