Antineutrophil cytoplasmic antibodies: a still-growing class of autoantibodies in inflammatory disorders

Cutaneous vasculitis

Vasculitis can range in severity from a self-limited single-organ disorder to a life-threatening disease with the prospect of multiple-organ failure. This condition presents many challenges to the physician, including classification and diagnosis, appropriate laboratory workup, treatment, and the need for careful follow-up. The physician must not only be able to recognize vasculitis but also be able to provide a specific diagnosis (if possible) as well as recognize and treat any underlying etiologic condition. Most diagnostic criteria are based on the size of vessel involvement, which often correlates with specific dermatologic findings. This may allow the dermatologist to provide an initial diagnosis and direct the medical evaluation. This article reviews the classification and diagnosis of cutaneous vasculitic syndromes and current treatment options; it also presents a comprehensive approach to diagnosing and treating the patient with suspected cutaneous vasculitis. (J Am Acad Dermatol 2003;48:311-40.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be familiar with the classification and clinical features of the various forms of cutaneous vasculitis. They should also have a rational approach to diagnosing and treating a patient with vasculitis.

Diagnostic value of anti-Saccharomyces cerevisiae and antineutrophil cytoplasmic antibodies for inflammatory bowel disease: high prevalence in patients with celiac disease

Both celiac disease and inflammatory bowel disease (IBD) are characterized by chronic diarrhea and the presence of distinct (auto)antibodies. In the present study we wanted to determine the prevalence of serological markers for inflammatory bowel disease, i.e., perinuclear antineutrophil cytoplasmic antibodies (pANCA) and/or anti-Saccharomyces cerevisiae antibodies (ASCA), in 37 patients with biopsy-confirmed celiac disease (Marsh IIIb/c). The majority of the patients was positive for IgA (auto)antibodies typically associated with celiac disease, i.e., antiendomysium antibodies (EMA) (86.5%), antigliadin antibodies (AGA) (73%), and antirecombinant human tissue transglutaminase antibodies (rh-tTGA) (86.5%). Four patients with selective IgA deficiency could be identified by analyzing EMA, AGA, and rh-tTGA for the IgG isotype. The prevalence of pANCA and ASCA, markers that are used for IBD, was unexpectedly high in our cohort of patients with celiac disease: 8 patients were positive for pANCA (IgG) and 16 patients were positive for ASCA (IgG and/or IgA). These results indicate that the presence of pANCA or ASCA in the serum of patients with chronic diarrhea does not exclude celiac disease. A prospective study is required to determine whether pANCA and/or ASCA identify patients at risk for developing secondary autoimmune disease.

Antineutrophil cytoplasmic autoantibody in the absence of Wegener's granulomatosis or microscopic polyangiitis: implications for the surgical pathologist

Antineutrophil cytoplasmic antibodies (ANCA) are useful serologic markers for the diagnosis and management of patients with Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA). However, problems in diagnosis and classification may occur when patients with other disorders develop ANCA. A 7-year review (1993-1999) disclosed 247 patients whose sera tested positively for ANCA by an indirect immunofluorescence method: 166 patients for cytoplasmic-ANCA (C-ANCA) and 81 patients for perinuclear-ANCA (P-ANCA) Twenty-seven patients had active pulmonary disease and underwent open-lung biopsy or transbronchial biopsy. Eight patients (30%) had a disease other than WG or MPA, and their clinical, pathological, and serological findings were reviewed. The patients, all women, ranged in age from 28 to 77 years (median, 37 y). Dyspnea (n = 6), cough (n = 6), chest pain (n = 2), and/or hemoptysis (n = 2) were present. The duration of symptoms lasted from 3 weeks to 6 years (median, 6 mo). ANCA titers were C-ANCA (n = 4; range, 1:40-1280) or P-ANCA (n = 4; range, 1:40-640). The lung biopsies disclosed nonspecific interstitial pneumonia (n = 4), bronchiolitis obliterans organizing pneumonia (n = 1), diffuse alveolar damage (n = 1), organizing diffuse alveolar hemorrhage without capillaritis (n = 1), and necrotic granuloma (n = 1). No cases showed characteristic histology for WG or MPA. The final diagnoses were various connective tissue disorders (n = 5), chronic hypersensitivity pneumonia (n = 1), postinfectious bronchitis/bronchiectasis (n = 1), and ulcerative colitis-related lung disease (n = 1). Surgical pathologists should be aware that significantly elevated ANCA titers may be associated with diverse forms of pulmonary disease. ANCA positivity alone, in the absence of appropriate clinical or pathologic findings, should not be used to substantiate a diagnosis of WG or MPA.

Antineutrophil cytoplasmic antibodies, anti-Saccharomyces cerevisiae antibodies, and specific IgE to food allergens in children with inflammatory bowel diseases

Differential diagnosis between ulcerative colitis (UC) and Crohn's disease (CD) is difficult in the initial phases in pediatric patients with inflammatory bowel diseases (IBD). This study was performed to determine the significance of anti-neutrophil cytoplasmic antibodies (ANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) in IBD. ANCA were specified with regard to their antigenic specifity, significance to the diagnosis, and correlation of titer with the disease activity. The occurrence of food allergy was questioned, too. Serum samples from 44 children with UC (n = 23) or CD (n = 21) and from disease-control children (coeliac disease, n = 21) were analyzed for IgG ANCA, ANCA target antigens, IgA and IgG ASCA, and IgE to food allergens. Results show that ANCA occur more frequently in UC than in CD and disease-control (74, 24, and 10%, respectively). The presence of ANCA does not reflect disease activity. Antigenic specificity does not differ in any group. IgA-ASCA are found more often in patients with CD (76% versus 17% in UC). The testing for both ANCA and ASCA enabled clear-cut differential diagnosis between UC and CD based on the high specificity (ANCA+ ASCA- 92.5% for UC, ANCA- ASCA+ 93.2% for CD). Specific IgE to food allergens were found in 8.7, 14.3, and 23.8% of patients with UC, CD, and coeliac disease, respectively. We conclude that combined testing of ANCA and ASCA represents a valuable tool in the differential diagnosis between UC and CD in pediatric patients, minimizing invasive diagnostic procedures. Monitoring of ANCA, its specificity, and titer determination does not bring more information. Testing for specific IgE to food allergens may be considered in individual patients.

AECA and ANCA in patients with premature atherosclerosis

Autoimmunity is suggested to play a pathogenetic role in premature atherosclerosis. Since atherosclerosis and vasculitis seem pathogenetically related, we hypothesized that ANCA, an important antibody in vasculitis, plays a role in atherosclerosis as well. We therefore investigated the prevalence of ANCA in patients with premature atherosclerosis and related the presence of these antibodies to levels of AECA and markers of inflammation.

METHODS & RESULTS

In a cohort of 286 patients with premature atherosclerosis the prevalence of ANCA was 5.6% (16/286). All had perinuclear ANCA. More females were ANCA-positive (8M/8F vs. 200M/70F, p = 0.03). In a nested case-control study, comparing the 16 ANCA-positive patients with 32 controls, levels of AECA were higher in the first (7.32 +/- 0.91U vs. 5.52 +/- 0.41U, p < 0.05).

CONCLUSION

ANCA does not seem to play a major role in premature atherosclerosis. Whether elevated levels of AECA in ANCA-positive patients with premature atherosclerosis reflect more extended vascular disease remains to be determined.

Hypertrophic pachymeningitis with anti-neutrophil cytoplasmic antibody (p-ANCA), and diabetes insipidus

We treated a patient with idiopathic cranial hypertrophic pachymeningitis and elevated serum titer of perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA) reactive against myeloperoxidase. This 67-year-old man showed multiple cranial nerve-palsies, central diabetes insipidus (DI), and an intrasellar mass. DI and intrasellar mass had been present for 3 years, and DI had been well controlled by intranasal desmopressin. His nerve-palsies were most likely caused by thickened dura matter detected by the brain MRI. Granuloma may develop in the sella, and MRI findings in our patient are compatible to it. Corticosteroid and oral cyclophosphamide therapy improved his neurological symptoms and serum p-ANCA level with showing good correlation. DI improved temporally for 2 months. Few other cases of hypertrophic pachymeningitis with elevated p-ANCA have been reported, however the etiology is unknown. As p-ANCA antibodies have been detected in many of vasculitides, microvasculitis may be involved in some cases of idiopathic hypertrophic pachymeningitis.

Autoantibody systems in rheumatoid arthritis: specificity, sensitivity and diagnostic value

The diagnosis of rheumatoid arthritis (RA) is primarily based on clinical symptoms, so it is often difficult to diagnose RA in very early stages of the disease. A disease-specific autoantibody that could be used as a serological marker would therefore be very useful. Most autoimmune diseases are characterized by a polyclonal B-cell response targeting multiple autoantigens. These immune responses are often not specific for a single disease. In this review, the most important autoantibody/autoantigen systems associated with RA are described and their utility as a diagnostic and prognostic tool, including their specificity, sensitivity and practical application, is discussed. We conclude that, at present, the antibody response directed to citrullinated antigens has the most valuable diagnostic and prognostic potential for RA.

Native and recombinant proteins to analyze auto-antibodies to myeloperoxidase in pauci-immune crescentic glomerulonephritis

The prevalence of Anti-Neutrophil Cytoplasmic Antibodies (ANCA) directed against myeloperoxidase (MPO) in pauci-immune necrotizing crescentic glomerulonephritis (NCGN) is dependent on the assay(s) used. We investigated the frequency of MPO-ANCA as detected by different assays for MPO-ANCA in a large cohort of patients with biopsy-proven pauci-immune NCGN. Sera from 121 consecutive untreated patients presenting with pauci-immune NCGN were tested for ANCA directed to proteinase-3 (PR3) at diagnosis. PR3-ANCA negative sera were tested by direct ELISA using recombinant or native MPO and by capture ELISA using two different specific monoclonal antibodies directed to MPO and three different antigenic sources. Sera from 80 relevant disease controls were tested to explore the specificity of the different assays. Thirty-eight out of 121 patients (31%) with pauci-immune NCGN did not have PR3-ANCA. Sufficient amounts of serum from 30 of these 38 PR3-ANCA negative patients were available for further testing. Recombinant and native MPO were recognized by similar numbers of sera in a direct ELISA (recombinant MPO: 93%, native MPO: 93%) and a capture ELISA (recombinant MPO: 77-87%, native MPO: 93%). Sera of patients with PR3-ANCA positive pauci-immune NCGN and disease controls were less frequently positive for MPO-ANCA in a capture ELISA (recombinant MPO: 3-7%, native MPO: 6-7%) than in a direct ELISA (recombinant MPO: 25%, native MPO: 13%). Both direct and capture ELISA assays using either native or recombinant MPO are sensitive techniques to detect MPO-ANCA in patients with pauci-immune NCGN. A capture ELISA performs better than a direct ELISA because it combines a higher specificity with a comparable sensitivity. Recombinant MPO is a good alternative for native MPO when used as antigen in a capture ELISA, but not when used in a direct ELISA because of lower specificity in this latter assay.

The role of metals in autoimmune vasculitis: epidemiological and pathogenic study

BACKGROUND

A possible relationship between Silica (Si) exposure and antineutrophil cytoplasm antibodies (ANCA)-associated vasculitis has been reported. Furthermore, tuberculosis (TBC) has been frequently described in patients with silicosis, and TBC infection shares with ANCA-associated vasculitis the formation of granulomas. Therefore, an intriguing network including Silica, Vasculitis, TBC and ANCA might be hypothesized. The aim of this work was to further investigate these correlations using both epidemiological and pathogenic approaches.

METHODS

Study I--epidemiological study. A case-control study to compare the occupational histories of 31 cases of biopsy proven vasculitis (18 pauci-immune crescentic glomerulonephritis, 9 microscopic polyangitis, 4 Wegener's granulomatosis) with those of 58 age, sex and residence-matched controls (affected by other kidney diseases), was performed. Occupational Health physicians designed an appropriate questionnaire in order to evaluate a wide spread of exposures and calculate their entity by the product of Intensity x Frequency x Duration. Study II--tuberculosis association. A case-control study to evaluate the frequency of a previous history of tuberculosis (TBC) in 45 patients with vasculitis and 45 controls were performed. Study III--ANCA positivity. A case-control study to evaluate the presence of ANCA was performed by testing blood samples of 64 people with previous professional exposure and 65 sex/age matched patients hospitalized in a General Medicine Unit. Furthermore, the same evaluation was made in a pilot study in 16 patients with ongoing or previous TBC. Study IV--experimental study. The oxygen free radicals (OFR) and IL-12 production (both involved in the pathogenesis of vasculitis) from human phagocytic cells stimulated with an amorphous (diatomaceous earth) and a crystalline (quartz) form of Si at the doses of 10 and 100 microg ml(-1) was evaluated.

RESULTS

Study I--a positive history of exposure to Si resulted in significantly more present in cases (14/31 = 45%) than in controls (14/58 = 24%, P = 0.04, OR = 2.4) and no other significant exposure association was found (including asbestos, mineral oil, formaldehyde, diesel and welding fumes, grain and wood dust, leather, solvents, fungicides, bitumen, lead and paint). Study II--past TBC infection was significantly more present in patients with vasculitis (12/45 = 26%) than in controls (4/45 = 8%, P < 0.05). Study III--ANCA was present in 2/64 exposed people (vs. 0/65 controls, P = NS) and 0/16 patients with TBC. Study IV--both amorphous and crystalline Si forms represented a stimulus for OFR and IL-12 production, but quartz resulted as a greater inductor.

CONCLUSIONS

We conclude that Si exposure might be a risk factor for ANCA-associated vasculitis, possibly enhancing endothelial damage by phagocyte generation of oxygen free radicals and Th1 differentiation by an excessive IL-12 phagocyte production. Frequency of TBC was significantly higher in vasculitis patients. ANCA was not frequent in the preliminary examination of people with previous professional exposure or patients with TBC, but the number of samples evaluated is too small to allow conclusions.

IgG from myeloperoxidase-antineutrophil cytoplasmic antibody-positive patients stimulates greater activation of primed neutrophils than IgG from proteinase 3-antineutrophil cytosplasmic antibody-positive patients

OBJECTIVE

Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) have been reported to be pathologically and clinically different. The aim of this study was to assess whether these differences could be explained by differing abilities of proteinase 3-antineutrophil cytoplasmic antibody (PR3-ANCA)-positive IgG preparations or myeloperoxidase-ANCA (MPO-ANCA)-positive IgG preparations to activate neutrophils (polymorphonuclear cells [PMN]) in vitro.

METHODS

Using Percoll density gradients, PMN were isolated (concentration 2 x 10(6)/ml) and primed with cytochalasin B (1 ng/ml) and tumor necrosis factor alpha (TNFalpha; 2 ng/ml). The PMN were activated with 200 microg/ml of normal IgG or ANCA. Activation was determined by 1) superoxide anion generation as determined by the superoxide dismutase-inhibitable reduction of ferricytochrome c, 2) monitoring fluxes in Ca2+ concentration using Fura 2-AM-loaded PMN, and 3) degranulation using an MPO assay. Surface expression of PR3 and MPO was determined by fluorescence-activated cell sorter analysis. ANCA isotypes were investigated by enzyme-linked immunosorbent assay.

RESULTS

Activation of PMN by MPO-ANCA-positive IgG preparations compared with PR3-ANCA-positive IgG preparations resulted in greater generation of superoxide anions (MPO-ANCA-positive IgG preparations 9.13 +/- 0.39 nmoles [mean +/- SEM], PR3-ANCA-positive IgG preparations 6.32 +/- 0.35 nmoles; P < 0.001), Ca2+ fluxes (MPO-ANCA-positive IgG preparations 0.735 +/- 0.10, PR3-ANCA-positive IgG preparations 0.33 +/- 0.098; P < 0.01), and MPO degranulation (MPO-ANCA-positive IgG preparations 251.98 +/- 26.7 ng, PR3-ANCA-positive IgG preparations 145.19 +/- 19.4 ng; P < 0.001). The increased activation seen with MPO-ANCA-positive IgG preparations was not due to increased expression of MPO on the cell surface, because following TNFalpha priming PR3 was expressed on significantly more cells than was MPO (PR3 expression 54.2 +/- 5.18%, MPO 31.6 +/- 3.55%; P < 0.001). IgG1 and IgG4 were the predominant isotypes in both MPO-ANCA-positive IgG preparations and PR3-ANCA. MPO-ANCA contained significantly more IgG1 than did PR3-ANCA, and PR3-ANCA-positive IgG preparations contained significantly more IgG3.

CONCLUSION

In vitro MPO-ANCA-positive IgG preparations are more activating than PR3-ANCA-positive IgG preparations. The increased activation cannot be explained by increased MPO expression on the cell surface or greater IgG3 present in MPO-ANCA-positive IgG preparations. Differences in activation of PMN by these antibodies may determine some differences between WG and MPA.

Autoantibodies Associated with Rheumatic Diseases

The identification of circulating autoantibodies contributes to the correct diagnosis as well as to the follow-up of rheumatic diseases. Some autoantibodies are even included in diagnostic and classification criteria for these types of autoimmune diseases. There are several relatively specific screening and identification methods for the measurement of autoantibodies available. The type of assay crucially influences the diagnostic value of the parameters. In general, routine laboratories should prefer enzyme immunoassays (ELISA) using well characterized antigens, although ELISA tests tend to produce more false-positive and true weakly positive results, which reduce their positive predictive value. Therefore one should be aware that laboratory results can only be properly interpreted when there is a correlation with the clinical situation and when the limitations of the technologies used for autoantibody identification have been taken into consideration. A diagnostic algorithm consisting of screening and identification steps should be established by each laboratory in order to create a rational, evidence-based and cost-effective basis for the diagnosis of rheumatic diseases.

Pulmonary capillaritis

Vasculitis, inflammation, and necrosis of blood vessels can involve any size or type of vessel in the pulmonary vasculature, including the capillaries, so-called capillaritis. Although pulmonary capillaritis is a histopathologic diagnosis that is not pathognomonic of a specific disorder, it usually signals the presence of an underlying systemic vasculitis or collagen vascular disease. Patients with pulmonary capillaritis usually present with bilateral infiltrates on chest radiographs and can be acutely ill with diffuse alveolar hemorrhage that may be life threatening. Therapy depends on diagnosis of the underlying disease that gave rise to the capillaritis. Since many of the disorders leading to capillaritis are treated by immunosuppression with corticosteroids and cyclophosphamide or azathioprine, infection must be excluded early in the course of therapy.

Antiproteinase 3- and antimyeloperoxidase-associated vasculitis

Antiproteinase 3- and antimyeloperoxidase-associated vasculitis. Wegener's granulomatosis, microscopic polyangiitis, and idiopathic pauci-immune necrotizing crescentic glomerulonephritis (NCGN) are strongly associated with antineutrophil cytoplasmic autoantibodies (ANCAs) directed against either proteinase 3 (anti-PR3) or myeloperoxidase (anti-MPO). This has led some investigators to prefer combining these diseases under the common heading of ANCA-associated vasculitides. However, it is increasingly recognized that there are characteristic differences between patients with anti-PR3 and those with anti-MPO-associated vasculitis. This review focuses on the clinical, histopathologic, and possibly pathophysiologic differences between anti-PR3- and anti-MPO-associated vasculitis. Although there is considerable overlap, the anti-PR3- and anti-MPO-associated vasculitides are each characterized by particular clinical and histopathological findings. Extrarenal organ manifestations and respiratory tract granulomas occur more frequently in patients with anti-PR3 than in those with anti-MPO. Anti-PR3-positive patients with NCGN generally have a more dramatic deterioration of their renal function compared with anti-MPO-positive patients. The term "ANCA-associated vasculitis" is considered as a useful concept in the presence of systemic vasculitis. Likewise, in the presence of vasculitis, the terms "anti-PR3-associated vasculitis" and "anti-MPO-associated vasculitis" are useful concepts.

Antineutrophil cytoplasmic antibodies (ANCA) and systemic vasculitis: update of assays, immunopathogenesis, controversies, and report of a novel de novo ANCA-associated vasculitis after kidney transplantation

OBJECTIVES

To characterize antineutrophil cytoplasmic antibodies (ANCA), their major autoantigens, disease associations, and pathophysiology in systemic vasculitides. To describe a patient with a novel de novo ANCA-associated vasculitis after kidney transplantation.

METHODS

We reviewed and compiled the literature on ANCA-related topics and systemic vasculitis. Laboratory and clinical data from a cadaveric kidney transplant patient who developed necrotizing vasculitis involving glomerular capillaries, with crescent formation associated with P-ANCA and myeloperoxidase, were analyzed.

RESULTS

Large-scale multi-center testing of patient and normal sera by the European ANCA Assay Standardization Project using immunofluorescence assays and enzyme immunoassays indicate the assays have good sensitivity and specificity, and diagnostic utility for ANCA-associated vasculitis. A few investigations covering basic and clinical research with ANCA remain controversial: whether endothelial cells do or do not express a 29-kd neutral serine protease termed proteinase-3 (PR-3), the target of ANCA in most individuals with Wegener's granulomatosis, and whether anti-myeloperoxidase (MPO) ANCAs recognize a restricted number of epitopes on MPO. This issue has relevance for using monoclonal antibodies to treat patients with vasculitis who have adverse effects from immunosuppressive drugs. The two allelic forms of FcgammaRIIa (H131/R131) and the two of FcgammaRIIlb (NA1/NA2) are discussed as possible inheritable genetic elements for vasculitic disorders and for signaling responses. Stimulatory and costimulatory molecules, and cytokine profiles of T lymphocytes are characterized to show that these cells are actively involved in the ANCA-associated vasculitides. The patient described had a de novo ANCA associated small vessel vasculitis which developed after renal transplantation.

CONCLUSIONS

There have been significant advances in the development of sensitive and specific ANCA assays. The immunopathogenetic mechanism of ANCA involves the constitutive FcgammaRs, ligands, and signaling responses to activate cytokine-primed neutrophils. This may lead to the generation of reactive oxygen intermediates, degranulation, and secretion of intracellular granule contents, and ultimately inflammation and vasculitis.

Identification of histone H1 as a cognate antigen of the ulcerative colitis-associated marker antibody pANCA

Perinuclear anti-neutrophil cytoplasmic antibody (pANCA)(4)is a predominant serum marker of ulcerative colitis (UC), and a familial trait associated with disease susceptibility and disease associated MHC haplotypes. This study characterizes the pANCA antigen defined by representative UC-pANCA human monoclonal antibodies, Fab 5-3 and 5-2. Western blot analysis probed with Fab 5-3 revealed specific binding to a nuclear protein doublet (apparent MW=32-33 kDa) expressed in several cell types. Purification and tryptic peptide sequencing identified the protein as histone H1, and this specificity was confirmed by Fab 5-3 binding to purified H1. Rabbit anti-histone H1 immunostaining and Western blot analysis confirmed that the pANCA epitope is preferentially immunoaccessible in polymorphonuclear neutrophils (PMN). The epitope was localized to the COOH-terminal region by site-specific proteolysis, and recombinant deletants further localized binding activity for both Fab 5-2 and 5-3 to two non-overlapping segments (AA 69-171 and 172-226) associated with a recurring PKKAK motif. Serum IgG binding was detectable to these segments, but was not significantly correlated with pANCA titer or disease status. These findings indicate that histone H1 bears a recurring COOH-terminal epitope recognized by monoclonal ulcerative colitis-associated pANCA marker antibodies, but this epitope is not a predominant specificity of serum pANCA.

Mast cell and neuroendocrine cytoplasmic autoantigen(s) detected by monoclonal pANCA antibodies

pANCA is a marker antibody expressed in most patients with ulcerative colitis, and its cognate antigen is potentially an immunologic target in this disease. This study evaluates whether pANCA detects an autoantigen that is expressed in the colonic mucosa. Immunohistochemistry of colon specimens with human pANCA monoclonal antibodies (Fab 5-2 and 5-3) revealed a minor population of immunoreactive mucosal cells bearing a cytoplasmic vesicle antigen. By distribution, morphology, and tryptase expression, these were identified as mast cells. Immunofluorescent analysis revealed similar immunoreactivity of mouse mast cell lines and human KU812. Western analysis of mouse mast cell lines revealed immunoreactive proteins, and these were distinct from previously proposed pANCA antigens (histone H1, HMG 1 and 2, and neutrophil vesicle antigens). Cognate antigen for Fab 5-2 and 5-3 was also expressed in other tissue mast cells, cerebellar neurons, and pancreatic islet cells. These findings identify a novel cytoplasmic autoantigen(s) associated with UC by its presence in colonic mucosa and recognition by a disease-associated marker antibody.

ELISA is the superior method for detecting antineutrophil cytoplasmic antibodies in the diagnosis of systemic necrotising vasculitis

BACKGROUND

Antineutrophil cytoplasmic antibodies (ANCA) have been used as a diagnostic marker for systemic necrotising vasculitis, a disease classification which includes Wegener granulomatosis, microscopic and classic polyarteritis nodosa, and Churg Strauss disease.

OBJECTIVE

To compare the diagnostic value of the two methods for detecting these antibodies--immunofluorescence and enzyme linked immunosorbent assay (ELISA)--with respect to biopsy proven active systemic necrotising vasculitis in a clinically relevant population.

METHODS

A prospective study to ascertain the patient's diagnosis at the time of each of the 466 requests for ANCA received at one laboratory over a nine month period, and allocate each to one of five diagnostic groups: active and inactive biopsy proven systemic necrotising vasculitis, suspected systemic necrotising vasculitis, low probability systemic necrotising vasculitis, and not systemic necrotising vasculitis.

RESULTS

ELISA was superior to immunofluorescence in the diagnosis of systemic necrotising vasculitis because it was less likely to detect other diseases. This was reflected in its specificity of 97% and positive predictive value of 73%, compared with 90% and only 50% for immunofluorescence (p = 0.0006 and p = 0.013, respectively). ELISA had a negative predictive value of 98% which was not significantly different to immunofluorescence. ELISA was technically superior.

CONCLUSIONS

ELISA is the superior method of ANCA detection in the diagnosis of systemic necrotising vasculitis and should be used in conjunction with a compatible clinical picture and histological evidence.

Are anti-neutrophil cytoplasmic antibodies (ANCA) clinically useful in inflammatory bowel disease (IBD)?

Since the first detection of ANCA in IBD, numerous studies have dealt with their prevalence, antigenic specificities, clinical significance, pathophysiological role, and their induction. This review summarizes the information obtained from those studies and shows that ANCA are not directly useful as diagnostic and prognostic factors in IBD. ANCA were detected in 50-85% of patients with ulcerative colitis (UC) and 10-20% of patients with Crohn's disease (CD). Multiple target antigens are recognized by these autoantibodies, including both cytoplasmic and nuclear proteins. A pathophysiological role for ANCA in IBD is far from clear. On the one hand, it is suggested that ANCA are genetic markers of susceptibility for IBD, and on the other hand, the induction of ANCA in those diseases may just be an epiphenomenon of chronic inflammation. We discuss recent evidence that ANCA may be induced by a break-through of tolerance towards bacterial antigens.

Antineutrophil cytoplasmic antibodies as markers for systemic autoimmune disease

Antineutrophil cytoplasmic antibodies (ANCA) have been associated with systemic vasculitis for almost 15 years. Significant advances in our understanding of the ANCA phenomenon have occurred with recognition of broadening the spectrum of diseases associated with ANCA, identification of specific antigens recognized by ANCA, and development of antigen specific assays for clinical use. Nevertheless problems continue for the chest physician in interpretation of this test. Although antigen specific testing improves overall performance of the test, accurate assessment of pretest probability of disease is still important for effective use of ANCA testing.

Antineutrophil cytoplasmic antibodies in primary sclerosing cholangitis: defined specificities may be associated with distinct clinical features

PURPOSE

The clinical significance of antineutrophil cytoplasmic autoantibodies (ANCA) in primary sclerosing cholangitis has not been established. We investigated whether analysis of the antigenic specificities of ANCA is useful for delineating clinical subsets of the disease.

METHODS

Sixty-nine patients with primary sclerosing cholangitis were studied. The presence of ANCA was analyzed by indirect immunofluorescence. Antibodies directed against specific antigens--proteinase 3, myeloperoxidase, elastase, bactericidal/permeability-increasing protein, cathepsin G, and lactoferrin--were identified by enzyme-linked immunosorbent assay.

RESULTS

ANCA were detected by indirect immunofluorescence in 46 (67%) patients. In antigen-specific enzyme-linked immunosorbent assays, 37 (55%) of the 69 patients had antibodies to one or more antigens: 32 (46%) had antibodies to bactericidal/permeability-increasing protein, 16 (23%) had antibodies to cathepsin G, and 15 (22%) had antibodies to lactoferrin. Only 3 patients had antibodies to proteinase 3. Antibodies to myeloperoxidase or elastase were not detected. Twenty (29%) patients had antibodies to different antigens simultaneously. ANCA as detected by indirect immunofluorescence were not significantly associated with the presence of cirrhosis nor with the coexistence of inflammatory bowel disease. However, antibodies to bactericidal/permeability-increasing protein and cathepsin G were both associated with the presence of cirrhosis, and antibodies to lactoferrin were more frequently detected in patients with primary sclerosing cholangitis in conjunction with ulcerative colitis than in those without inflammatory bowel disease.

CONCLUSION

Defined specificities of ANCA in primary sclerosing cholangitis may be related to particular clinical features of the disease.

Anti-phagocyte antibodies and infection

Autoantibodies specific to the cytoplasmic components of neutrophils and monocytes are associated with vasculitis and other idiopathic inflammatory disorders. In this study, using enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assays, sera from patients with acute and chronic infection were examined for the presence of anti-neutrophil and anti-monocyte antibodies: cystic fibrosis (n = 23), acute appendicitis (n = 22), tuberculosis (n = 26), acute gastroenteritis (n = 38), bronchiectasis (n = 9) and chronic granulomatous disease (n = 6). Sera from patients with Wegener's granulomatosis (n = 14), rheumatoid factor positive (n = 15) and healthy volunteers (n = 20) were used as positive and negative controls. In patients with chronic infection, using an ELISA assay, antibodies reactive with neutrophil or monocyte components (% reacting with monocyte components in parenthesis) were found in: 70% (39%) of patients with cystic fibrosis, 4% (38%) of patients with tuberculosis, 0% (33%) of patients with bronchiectasis and 0% (17%) of patients with chronic granulomatous disease. When these sera were examined using an immunofluorescence assay, all of the positive samples were found to react with the cytoplasmic component of neutrophils or monocytes. In patients with acute infection no antibodies (either IgG or IgM) were detected against neutrophils or monocytes. These findings imply that antibodies directed against neutrophil cytoplasmic components are predominantly associated with chronic pyogenic infection and antibodies specific to monocyte cytoplasmic components are predominantly associated with chronic granulomatous infection. This mirrors the findings in idiopathic inflammatory disease where anti-monocyte antibodies are associated with granulomatous disorders such as sarcoidosis, and anti-neutrophil antibodies are associated with neutrophilic disorders such as ulcerative colitis. These results suggest that chronic stimulation of phagocytes by infectious agents may result in the generation of a humoral response against phagocyte cytoplasmic components. This furthers our understanding of humoral immune responses against phagocytic cell components during infection.

Disease spectrum of patients with antineutrophil cytoplasmic autoantibodies of defined specificity: distinct differences between patients with anti-proteinase 3 and anti-myeloperoxidase autoantibodies

OBJECTIVE

To compare the disease spectrum of consecutive patients with antineutrophil cytoplasmic autoantibodies directed against proteinase 3 (anti-PR3) or myeloperoxidase (anti-MPO).

DESIGN

Retrospective analysis.

SETTING

Three teaching hospitals in the Netherlands.

MAIN OUTCOME MEASURES

Clinical features at presentation, histopathological characteristics and outcome.

SUBJECTS

All consecutive patients who tested positive for anti-PR3 (n=46) or anti-MPO (n=46) over an 8-year-period.

RESULTS

At diagnosis, patients with anti-PR3 had a higher vasculitis activity index than patients with anti-MPO (P < 0.001). The mean (SD) number of affected organs in the anti-PR3 group exceeded that of the anti-MPO group (3.9 (1.4) and 2.2 (1.1), respectively; P < 0.01). The combination of renal and respiratory tract involvement was present in as many as 78.3% of patients with anti-PR3 and in only 23.9% of patients with anti-MPO (P < 0.01). Renal-limited disease exclusively occurred in patients with anti-MPO. Granulomas were found in 41.3% of anti-PR3- but in only 4.3% of anti-MPO-positive patients (P < 0.01). All anti-PR3-positive patients had Wegener's granulomatosis or microscopic polyangiitis. By contrast, diagnoses in the anti-MPO group were more diverse: idiopathic necrotizing crescentic glomerulonephritis (26.1%), microscopic polyangiitis (26.1%). Churg-Strauss syndrome (4.3%), Wegener's granulomatosis (2.2%), giant cell arteritis (2.2%), clinically suspected vasculitis (19.6%), as well as miscellaneous nonvasculitic disorders (19.6%). During follow-up, 10 anti-PR3-positive patients had 11 relapses whereas only 3 patients with anti-MPO relapsed (P=0.04).

CONCLUSION

A large divergence was seen in the disease spectrum between patients with anti-PR3 and those with anti-MPO. In particular, extra-renal disease manifestations, granuloma formation and relapses were more prominent in anti-PR3- than in anti-MPO-positive patients.

Patients hospitalized because of small vessel vasculitides with renal involvement in the period 1975-95: organ involvement, anti-neutrophil cytoplasmic antibodies patterns, seasonal attack rates and fluctuation of annual frequencies

OBJECTIVES

To study organ involvement, anti-neutrophil cytoplasmic antibodies (ANCA) patterns, trends in yearly frequencies and seasonal variations of symptom onset in patients hospitalized because of small vessel vasculitides during a 21 year period (1975-95).

DESIGN

A retrospective investigation was conducted of 138 patients hospitalized with a diagnosis of small vessel vasculitides, as defined by the Chapel Hill Consensus Conference, within the County of Orebro, a mixed urban and rural area of central Sweden.

SETTING

Orebro Medical Center Hospital, Orebro, Sweden and two district hospitals within the County of Orebro, Sweden.

RESULTS

During the studied period there were 19 patients with a diagnosis of Wegener's granulomatosis (WG), 70 patients with microscopic polyangiitis (MPA), 36 patients with renal limited vasculitis (RLV), two with Churge-Strauss vasculitis (C-S), seven with Henoch-Schönleins purpura (HSP) and four with essential cryoglobulinemic vasculitis (ECV). Renal involvement was present in 123 patients (89.1%). A positive c- and/or pANCA was found in nearly 90% of the 111 patients where sera were available. Calculations of frequency data, restricted to the primary catchment area for patients with ANCA associated vasculitis and renal involvement (WG, MPA, RLV) during a 21-year period (1975-95) gave a mean annual frequency of 1.6 per 100,000 adults (95% CI: 1.2-3.1); for this group of patients with the inclusion of those with C-S, HSP and ECV during the last 10 year period (1986-95) gave a mean annual frequency of 2.5 per 100,000 adults (95% CI: 1.7-3.4), for male adults 3 per 100,000 (95% CI: 1.6-4.4), and female adults 1.9 (95% CI: 0.9-2.8). A frequency peak of 6.3 per 100,000 was seen for men aged 55-64. A periodic fluctuation of the frequencies with peaks every 3-4 years was noted for patients with ANCA related vasculitis (WG, MPA, RLV) during the 21-year period 1975-95. Onset of symptoms was predominantly noticed during the winter months (December-February) for patients with a positive cANCA.

CONCLUSION

The observed frequencies in our study of patients with small vessel vasculitides were higher than those previously documented. We also showed a periodic fluctuation of the annual frequencies and a seasonal variation of symptom onset.

Polyarteritis nodosa, microscopic polyangiitis and Churg-Strauss syndrome

Polyarteritis nodosa (PAN), first described by Küssmaul and Maier, is a well-known form of necrotizing angiitis whose manifestations are weight loss, fever, asthenia, peripheral neuropathy, renal involvement, musculoskeletal and cutaneous manifestations, hypertension, gastrointestinal tract involvement, and cardiac failure. Recently individualized from PAN, microscopic polyangiitis (MPA) is a systemic vasculitis of small-size vessels whose clinical manifestations are very similar to those of PAN, but it is characterized by the presence of rapidly progressive glomerulonephritis (RPGN), which is nearly constant, and pulmonary involvement usually absent in PAN. Churg Strauss syndrome (CSS) is a disorder characterized by hypereosinophilia and systemic vasculitis similar to that of PAN and occurring in individuals with asthma and allergic rhinitis. Considering the etiologies of PAN, primary and secondary vasculitides can also be distinguished because PAN can be the consequence of hepatitis B virus (HBV) infection and sometimes of other etiologic agents. The prognosis of systemic vasculitides has been transformed by corticosteroids that are, except in HBV-related PAN, the basic treatment. Immunosuppressive drugs, especially cyclophophamide, have also contributed to improving the prognosis, but their precise role in the management of these vasculitides is still being elucidated.

T lymphocyte responses to anti-neutrophil cytoplasmic autoantibody (ANCA) antigens are present in patients with ANCA-associated systemic vasculitis and persist during disease remission

ANCA with specificity for myeloperoxidase (MPO) and proteinase 3 (PR3) are present in patients with systemic vasculitis. The aim of this work was to determine whether such patients have T cell responses to these antigens and whether these responses are related to disease activity. Peripheral blood lymphocytes from 45 patients and 19 controls were cultured with ANCA antigens and proliferation measured. The antigens used were heat-inactivated (HI) MPO, HI PR3, native (non-HI) PR3, HI whole alpha-granules, and 25 overlapping peptides covering the entire PR3 sequence. Significant responses to both whole PR3 preparations were seen from patient and control groups, and to the alpha-granules from the patient group. Patients responded at all stages of disease: active, remitting, treated or untreated. Only two patients responded significantly to MPO. Responses were significantly higher with the patient group than the control group to all four whole ANCA antigens. Responses to those PR3 peptides containing epitopes known to be recognized by ANCA were detected from one patient. Thus, these studies demonstrate that T cells from vasculitis patients can proliferate to PR3 and occasionally to associated ANCA antigens. Further, responses may persist even after disease remission has been achieved.

Antineutrophil cytoplasmic antibody (ANCA)-positive cutaneous leucocytoclastic vasculitis associated with antithyroid therapy in Graves' disease

Presented is a case of a 27-year-old male with Graves' disease on long-term propylthiouracil treatment who, when changed to carbimazole, rapidly developed a petechial and purpuric eruption on the legs, which subsequently flared on treatment with radioiodine. The clinical diagnosis of leucocytoclastic vasculitis was confirmed on skin biopsy. High-titre antineutrophil cytoplasmic antibodies in a perinuclear pattern (P-ANCA) were identified. No anti-myeloperoxidase activity was noted; therefore, the P-ANCA were classified in the atypical group. The target antigens, as determined by enzyme-linked immunosorbent assay, were lysozyme, lactoferrin and bactericidal/permeability increasing protein. Propylthiouracil and carbimazole are chemically related antithyroid drugs. There are reports of typical and atypical P-ANCA-positive cutaneous vasculitis due to propylthiouracil. Cutaneous vasculitis associated with atypical P-ANCA has not been noted previously to be temporally related to carbimazole use. The consideration of thionamides as possible aetiological agents in cases of P-ANCA-positive drug-induced vasculitis is suggested.

Catalase and alpha-enolase: two novel granulocyte autoantigens in inflammatory bowel disease (IBD)

In IBD, the target antigens of anti-neutrophil cytoplasmic autoantibodies (ANCA) have not been fully identified, which limits the analysis of the diagnostic significance as well as of the possible pathophysiological role of these antibodies. In this study, we identify the target antigens of ANCA in large groups of patients with ulcerative colitis (UC) and Crohn's disease (CD). Apart from antibodies against lactoferrin and bactericidal/permeability-increasing protein (BPI), which have been reported before, antibodies against two novel granulocyte antigens were identified: antibodies against a 57/56-kD doublet were found in 38% of samples from UC patients and in 26% of samples from CD patients, whereas antibodies against a 47-kD protein were found in 10% of samples from UC patients and in 18% of samples from CD patients. Partial purification and amino acid sequence analysis identified the 57-kD protein as catalase and the 47-kD protein as alpha-enolase. This study is the first to report catalase and alpha-enolase as granulocyte antigens for autoantibodies in IBD.

Systemic vasculitis. Diagnostic clues to this confusing array of diseases

Systemic vasculitis can be difficult to recognize because of the many types of the disease and the conditions that can mimic it. However, early identification and initiation of treatment (often empirical) are important to avoid severe morbidity. In this symposium article, Dr Bush clearly describes the most common types of vasculitis according to current nomenclature based on the size of affected vessels. Illustrations of common signs of the various types of vasculitis are also included.

Central nervous system vasculitis

Vasculitis is inflammation of blood vessel walls, which produces dysfunction in both the peripheral and central nervous system (CNS). Cerebral ischemia is the major cause for neurological manifestations of CNS vasculitis. Unfortunately, a universally accepted classification of vasculitis has not emerged. Vasculitis affecting the CNS alone is referred to as primary angiitis of the CNS; secondary vasculitis occurs in association with a variety of conditions, including infections, drug abuse, lymphoproliferative disease and connective tissue diseases. The pathogenesis of vasculitis includes different immunological mechanisms. Recently, anti-neutrophil cytoplasmatic antibody (ANCA) has been demonstrated to play an active role in the immunopathogenesis of the vasculitis. Diagnosis of vasculitis depends on a combination of clinical, radiographic and pathologic features. A wide spectrum of clinical features may occur. The most typical clinical picture of CNS vasculitis is troke, encephalopathy or seizures. Assays for ANCA, serum cytokines, antibodies to endothelial cell antigens have been reported to be useful in diagnosing or monitoring the disease activity. The gold standard in diagnosis is confirmation of vasculitis in a biopsy specimen. Angiography may suggest the diagnosis but no abnormalities are pathognomonic. Ideally, the therapy of each vasculitis would focus on the specific immunologic mechanism causing the disease. Such specific interventions are not yet available. In general the most important approaches induce global immunosuppression. The goal of therapy, however, is to prevent recurrence of disease.

Assessment of disease activity in systemic vasculitis

The systemic vasculitides are a group of inflammatory disorders characterised by relapses and remission. Before the introduction of immunosuppressive drugs, mortality was unacceptably high. Immunosuppressive therapy has had a therapeutic impact, but at the cost of increased risk of infection and other adverse effects. Differentiating infection from active disease can be difficult, and the inappropriate prescription of immunosuppressive drugs can be fatal. Hence disease indices which can aid physicians to identify the active phase of disease and enable early treatment, will be valuable in the management of this group of disorders.

Misleading clinical features in Wegener's granulomatosis. A case report

Wegener's granulomatosis is a systemic vasculitis that may present with a variety of findings and be difficult to diagnose. We report a case of a patient who presented with serous otitis media and subsequently developed a suspected primary lung tumour. Thoracotomy and pulmonary mass excision were required to establish the diagnosis. Otological manifestations of Wegener's granulomatosis, differential diagnosis, pathological findings and c-ANCA test role are discussed.

Classification and management of necrotising vasculitides

Systemic vasculitides are a heterogeneous group of diseases. Having only a partial understanding of the aetiologies and pathogenetic mechanisms of these disorders explains the difficulties encountered in classifying and treating patients. Nevertheless, some important points have been established. Classification is mainly based on the size of vessels affected and, from the polyarteritis nodosa group, microscopic polyangiitis (MPA) has been separated from classic polyarteritis nodosa (c-PAN). The latter is a rare disease which is, in a small number of cases, the consequence of hepatitis B or C virus (HBV/HCV) infection. In the other cases of c-PAN and in MPA, the aetiology is unknown as for Churg-Strauss syndrome (CSS) and Wegener's granulomatosis (WG). MPA, CSS and WG are mainly antineutrophil cytoplasmic antibodies (ANCA)-related vasculitides. ANCA play a part in the pathogenesis of diseases and are sometimes useful markers for diagnosis and follow-up. Vasculitis treatments should be chosen according to classification, aetiology, pathogenetic mechanisms, severity and predictable outcome. In virus-associated vasculitides, treatment is based on the combination of antiviral agents and symptomatic or immunomodulating therapies. HBV-related PAN and HCV-related cryoglobulinaemia respond to interferon-alpha and to plasma exchange. Responses are excellent in HBV-PAN but usually partial in HCV-cryoglobulinaemia, and relapses occur in the majority of cases. MPA, c-PAN, WG and other vasculitides respond to corticosteroids and cytotoxic agents, mainly cyclophosphamide. Treatment duration and ways of administration can vary from one disease to another. Plasma exchange is not recommended as the first-line treatment. Immunoglobulins and other immunomodulating treatments are indicated in limited cases and their indications necessitate further prospective studies.

Identification of an autoantibody against alpha-enolase in primary biliary cirrhosis

BACKGROUND

Primary biliary cirrhosis is a chronic cholestatic liver disease in which autoreactive T cells may play an important role in the destruction of intrahepatic bile ducts. However, target antigens remain unknown. Alpha-enolase-derived peptide binds to human leukocyte antigen (HLA)-DR8, which is implicated in the development of primary biliary cirrhosis in Japanese patients. Partial homology between alpha-enolase and the inner lipoyl domain of E2 component of pyruvate dehydrogenase (PDH-E2) is also observed.

METHODS

Using alpha, beta and gamma enolase isozymes obtained from humans and/or rabbits, we examined serum samples of 56 patients with primary biliary cirrhosis, 19 autoimmune hepatitis, 38 acute and chronic viral hepatitis and 36 healthy subjects by immunoblotting.

RESULTS

Anti-alpha-enolase antibody was present in a significantly higher percentage of patients with primary biliary cirrhosis (16 of 56, 28.6%) and autoimmune hepatitis (6 of 19, 31.6%) than in normal subjects (p<0.005, p<0.01, respectively). Antibodies against beta and gamma-enolases were not detected in any serum sample. Although there was no significant correlation between the presence of anti-alpha-enolase antibody and clinical features of primary biliary cirrhosis, the mortality rate associated with hepatic failure in patients with positive autoantibody was significantly higher than that of antibody-negative PBC patients (6 of 16, 37.5% vs 5 of 40, 12.5%, p<0.05).

CONCLUSIONS

Since alpha-enolase is expressed on the cell surface, our data suggest that the immunological reaction to alpha-enolase might be involved in biliary epithelial destruction and be relevant to the disease progression.

Rupture of a hepatic artery aneurysm caused by Wegener's granulomatosis

Among vasculitis syndromes Wegener's granulomatosis (WG) is characterized by involvement of the upper and lower airways and kidneys. The associated vasculitis involves small and medium sized arteries and veins. Aneurysm formation and a segmental pattern of involvement of larger arteries is not typically seen in WG--a presentation more in keeping with polyarteritis nodosa. We report on a patient hospitalized with classical manifestations of WG who died suddenly of hypovolemic shock caused by intraperitoneal hemorrhage resulting from rupture of a hepatic artery aneurysm. The aneurysm was caused by involvement of the hepatic artery in the disease process. To our knowledge aneurysmatic dilatation of the hepatic artery due to WG has not been previously described. This case illustrates an unusual disease course in WG and the overlap which exists in classical vasculitis syndromes.

Pulmonary capillaritis and alveolar hemorrhage. Update on diagnosis and management

Pulmonary vascular inflammatory disorders may involve all components of the pulmonary vasculature, including capillaries. The principal histopathologic features of pulmonary capillaritis include capillary wall necrosis with infiltration by neutrophils, interstitial erythrocytes, and/or hemosiderin, and interalveolar septal capillary occlusion by fibrin thrombi. Immune complex deposition is variably present. Patients often present clinically with diffuse alveolar hemorrhage, which is characterized by dyspnea and hemoptysis; diffuse, bilateral, alveolar infiltrates on chest radiograph; and anemia. Pulmonary capillaritis has been reported with variable frequency and severity as a manifestation of Wegener's granulomatosis, microscopic polyarteritis, systemic lupus erythematosus, Goodpasture's syndrome, idiopathic pulmonary renal syndrome, Behçet's syndrome, Henoch-Schönlein purpura, IgA nephropathy, antiphospholipid syndrome, progressive systemic sclerosis, and diphenylhydantoin use. In addition to history, physical examination, and routine laboratory studies, certain ancillary laboratory tests, such as antineutrophil cytoplasmic antibodies, antinuclear antibodies, and antiglomerular basement membrane antibodies, may help diagnose an underlying disease. Diagnosis of pulmonary capillaritis can be made by fiberoptic bronchoscopy with transbronchial biopsy, but thoracoscopic biopsy is often employed. Since many disorders can result in pulmonary capillaritis with diffuse alveolar hemorrhage, it is crucial for clinicians and pathologists to work together when attempting to identify an underlying disease. Therapy depends on the disorder that gave rise to the pulmonary capillaritis and usually includes corticosteroids and cyclophosphamide or azathioprine. Since most diseases that result in pulmonary capillaritis are treated with immunosuppression, infection must be excluded aggressively.

[Pleuropulmonary manifestations of systemic vasculitis]

Pleuropulmonary manifestations of systemic vasculitis are common, polymorphic and of ambiguous significance: the same pulmonary lesion may reveal a specific manifestation of vasculitis as well as a therapy-induced complication, especially infection which may favor per se a flare-up. Two questions will be successively studied: what are the pleuropulmonary characteristics of Wegener's granulomatosis, Churg-Strauss syndrome, periarteritis nodosa, Behçet's disease, Takayasu's disease and temporal arteritis? What are the major adverse effects that may occur in the course of a treated systemic vasculitis?

Respiratory failure in ANCA-associated vasculitis

OBJECTIVE

To assess the prevalence, clinical manifestations, and course of respiratory failure in all patients who tested positive for antineutrophil cytoplasmic autoantibodies (ANCA) in our clinics in the period between January 1985 and January 1993.

DESIGN

Case-series analysis.

SETTING

Three teaching hospitals in the Netherlands.

PATIENTS

Two hundred twenty consecutive patients suspected of having vasculitis and/or glomerulonephritis who tested positive for ANCA by indirect immunofluorescence and enzyme-linked immunosorbent assay.

RESULTS

Sixty-two patients had pulmonary involvement. Acute respiratory failure developed in nine. Respiratory failure was related to infections in two of them and to ANCA-associated vasculitis in seven. These seven patients uniformly presented with pulmonary hemorrhage and diffuse pulmonary infiltrates. The diagnosis of systemic vasculitis was supported by the presence of a pulmonary-renal syndrome in all patients, and by detection of antibodies to the proteinase 3 or myeloperoxidase antigen in all but one patient. Antiglomerular basement membrane antibodies were absent. The mortality was high due to hypoxic respiratory failure, pulmonary superinfections, and concomitant renal failure.

CONCLUSIONS

Acute respiratory failure due to vasculitis developed in one of every nine patients with ANCA-associated pulmonary disease. Patients usually present with pulmonary infiltrates and hemoptysis. A diagnosis of vasculitis may be further supported by analysis of the urinary sediment and determination of the ANCA target antigen. It remains to be proved that early detection of ANCA favorably affects the outcome.

Antibodies to neutrophil elastase: a study in patients with vasculitis

Whether antibodies to elastase (EL) exist in autoimmune disease is controversial, due in part to inadequate methods used to determine antibody titers. We have developed a highly sensitive and specific enzyme-linked immunosorbent assay, using immobilized EL and mouse monoclonal antibodies for standardization. The specificity of the enzyme-linked immunosorbent assay was confirmed by absorption studies and Western blot analysis. Using this enzyme-linked immunosorbent assay, antibodies to EL were found in antineutrophil cytoplasmic antibody-positive vasculitis patients to a higher degree than reported in the literature (in eight of 108 patients with Wegener's granulomatosis and in 15 of 78 patients with microscopic polyangiitis). Patients with Wegener's granulomatosis or microscopic polyangiitis and antibodies to EL had significantly more severe renal involvement, as indicated by the higher frequency of dialysis dependency. Also in contrast to reported data, antibodies to EL were found less frequently in patients with systemic lupus erythematosus (nine of 64 patients). Binding of systemic lupus erythematosus sera to uncoated plates, giving a nonspecific reaction, was seen quite frequently, which might explain the discrepancy.

Two spatially distant epitopes of human lactoferrin

Lactoferrin (LF) is an iron binding protein, which may represent a target for antineutrophil cytoplasmic antibodies (ANCA) in patients affected by rheumatoid arthritis, ulcerative colitis, and primary sclerosing cholangitis. Here we describe the production and characterization of two new monoclonal antibodies (MAbs) against human LF. These MAbs (AGM 10.14, an IgG1, and AGM 2.29, an IgG2b) recognize spatially distant epitopes of LF as assessed by cross-blocking experiments. We also demonstrated by indirect immunofluorescence that both MAbs react with ethanol-fixed neutrophil granulocytes showing a perinuclear staining pattern. AGM 2.29 and AGM 10.14 have been utilized as capture and labeled tracer antibody, respectively, in a double determinant immunoassay (DDIA) to measure soluble LF. The results obtained show that this DDIA allows us to quantify even low concentrations of LF, the maximal range of the assay sensitivity being between 12 and 780 ng/ml. Therefore, AGM 10.14 and AGM 2.29 may represent useful reagents for studying the role of autoantibodies to LF as well as for measuring soluble LF, which is a reliable secretory marker of neutrophil activation.