Diagnostic value of standardized assays for anti-neutrophil cytoplasmic antibodies in idiopathic systemic vasculitis. EC/BCR Project for ANCA Assay Standardization

Disease of the month. The Churg Strauss Syndrome

The Churg Strauss Syndrome is an eosinophil-associated small vessel vasculitis. Although its pathogenesis may be distinctive and the association with severe late-onset asthma typical, the clinical features during the vasculitic phase widely overlap with those of the other forms of necrotizing vasculitis, and no single clinical or histologic feature is pathognomic of the condition. Renal involvement is common, although usually mild, and even when severe it tends to respond well to treatment. The prognosis for both patient and renal survival with adequate treatment is in general good. The optimal treatment strategy, however, is uncertain, and may differ from that for the other vasculitides. In particular, in contrast to Wegener's granulomatosis, the need for routine cyclophosphamide treatment is unconfirmed and requires further study.

ANCA-associated glomerulonephritis: Relationship of main ANCA subtypes to renal outcome, age and sex of the patients

BACKGROUND

Antineutrophil cytoplasmic antibodies (ANCA) have been proven to be useful diagnostic tools in patients with systemic vasculitis and glomerulonephritis. These antibodies exist in two types, a cytoplasmic pattern (cANCA) and a perinuclear pattern (pANCA). The effect of the main ANCA subtypes on renal outcome and its relationship to demographic findings and clinical features of patients with ANCA-associated glomerulonephritis has not been adequately studied.

PATIENTS AND METHOD

In this prospective study, we compared the clinical features at presentation and the renal outcome after 1 year of follow-up between two groups of patients with cANCA (n=22) and pANCA (n=29) consecutively encountered over a one-year period.

RESULT

At presentation, rapidly progressive glomerulonephritis (RPGN), and after 1 year of follow-up, endstage renal disease (ESRD) were seen more commonly in patients with pANCA than cases with cANCA (P=0.001 and P=0.004, respectively). Seropositivity for cANCA was more common in male and pANCA in female patients (P=0.005). Occurrence of the pulmonary-renal syndrome or extra-renal manifestations, such as sinusitis and skin rash, did not differ significantly among the two groups of patients with cANCA and pANCA.

CONCLUSION

Patients with pANCA present more frequently with RPGN, leading to a poorer renal survival compared to cases with cANCA. RPGN and pANCA are more common in females.

Sequential development of anti-GBM nephritis and ANCA-associated Pauci-immune glomerulonephritis

The medical history is presented of a 23-year-old man experiencing three episodes of pulmonary-renal syndrome. On the first occasion, a diagnosis of anti-glomerular basement membrane (GBM) disease (with linear deposition of immunoglobulin G [IgG] along the GBM) was made, whereas anti-neutrophil cytoplasmic autoantibodies were also present in serum. On the third occasion, 5 years later, p-ANCA-associated vasculitis (with pauci-immune crescentic glomerulonephritis) was diagnosed, whereas anti-GBM antibodies were absent. The current literature on ANCA-positive anti-GBM disease is briefly reviewed. A substantial proportion (20% to 30%) of patients with histologically and serologically proven anti-GBM nephritis display the presence of ANCA as well. In this group of patients with dual antibodies, clinical and histological findings suggest that ANCA are not merely epiphenomena, but are of pathogenetic importance and might be responsible for an initial vasculitic insult to the kidney with resultant secondary anti-GBM nephritis. The clinical course in our patient lends further support to this concept. Histological demonstration of anti-GBM nephritis followed by ANCA-associated pauci-immune glomerulonephritis in a single patient has not been reported before.

Mooren ulcer in South India: serology and clinical risk factors

PURPOSE

To investigate the rate of undiagnosed rheumatologic diseases and hepatitis C infection among patients with the clinical diagnosis of Mooren ulcer seen at Aravind Eye Hospital, Madurai, South India.

METHODS

Twenty-one patients with the clinical diagnosis of Mooren ulcer and 44 control patients underwent a complete ophthalmic history and examination, as well as serologic testing for antinuclear antibodies, rheumatoid factor, antineutrophil cytoplasmic antibodies, herpes simplex virus 1 antibodies, and hepatitis C virus antibodies.

RESULTS

There were no statistically significant differences in the rates of seropositivity for antinuclear antibodies, rheumatoid factor, antineutrophil cytoplasmic antibodies, herpes simplex virus 1 antibodies, and hepatitis C virus antibodies between patients with Mooren ulcer and control patients. Two patients with Mooren ulcer and four control patients were found to have a rheumatoid factor titer of greater than 1:20. One of the control patients, but none of the patients with Mooren ulcer, was found to have serologic evidence of hepatitis C infection. A history of corneal trauma, surgery, or infection was reported by 68% of patients with Mooren ulcer, compared with 20% of control patients (P < .001). Among patients with Mooren ulcer, bilateral disease occurred in 37% of patients, visual acuity was reduced to light perception in 15% of eyes, and perforation occurred in 19% of eyes.

CONCLUSIONS

Nineteen (90%) of 21 patients with the clinical diagnosis of Mooren ulcer were found to have no evidence of an underlying rheumatologic disease by history, examination, or serologic testing, and none was seropositive for hepatitis C. However, patients with Mooren ulcer were more likely than control patients to report a history of corneal trauma, surgery, or infection.

Glomerulonephritis

The differential diagnosis of glomerulonephritis without systemic disease includes poststreptococcal glomerulonephritis, IgA nephropathy, rapidly progressive glomerulonephritis (RPGN), and membranoproliferative glomerulonephritis (MPGN). Glomerular inflammation is probably induced directly by a nephritogenic streptococcal protein in poststreptococcal glomerulonephritis, and by mesangial deposition of abnormally glycosylated IgA1-containing immune aggregates in IgA nephropathy. In crescentic RPGN the role of cellular rather than humoral immune mechanisms is now becoming clear. Many patients with MPGN have chronic hepatitis C infection. There is no effective disease-specific therapy for poststreptococcal glomerulonephritis or IgA nephropathy. RPGN benefits from high-dose steroids and cytotoxic drug therapy with the addition of plasma exchange in disease induced by antibody to glomerular basement membrane. Antiviral therapies reduce the severity of MPGN due to hepatitis C virus. However, various new therapies directed at specific cytokines, growth factors, fibrin deposition, and other mediators of injury are being developed, as well as more specific and less toxic forms of immunotherapy.

What is new with anti-neutrophil cytoplasmic antibodies: diagnostic, pathogenetic and therapeutic implications

Anti-neutrophil cytoplasmic antibodies, as detected by indirect immunofluorescence, have limited diagnostic significance as they occur in a variety of inflammatory disorders. The presence of antibodies to defined target antigens of anti-neutrophil cytoplasmic antibodies, that is proteinase 3 and myeloperoxidase, is, however, highly specific for one of the systemic vasculitides, in particular Wegener's granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome, and idiopathic pauci-immune necrotizing crescentic glomerulonephritis. In general, anti-proteinase-3-positive patients show more widespread organ involvement, more granuloma formation, and a more severe initial course of their renal lesions than anti-myeloperoxidase-positive patients; however, there is considerable overlap, and either antibody specificity may be found in the different clinical syndromes. In vitro, anti-neutrophil cytoplasmic antibodies are able further to activate pre-activated neutrophils and monocytes, which can result in endothelial damage. A direct activating effect of anti-neutrophil cytoplasmic antibodies on endothelial cells has been suggested, but those studies should be confirmed. In vivo, experimental data support a pathogenetic role for anti-neutrophil cytoplasmic antibodies, particularly anti-myeloperoxidase, but besides anti-neutrophil cytoplasmic antibodies a second pro-inflammatory stimulus seems to be required to induce lesions. Whether anti-neutrophil cytoplasmic antibodies can be a direct target for treatment has still to be proved. Current immunosuppressive treatment regimens for the anti-neutrophil cytoplasmic antibody-associated vasculitides are, however, unsatisfactory because of side-effects, that is opportunistic infections and malignancies. New treatment regimens, based on new pathogenetic concepts, are currently being tested.

Serial measurements of antineutrophil cytoplasmic autoantibodies in patients with systemic vasculitis

PURPOSE

To assess the value of serial determinations of antineutrophil cytoplasmic autoantibodies (ANCA) for monitoring disease activity in patients with systemic vasculitis.

PATIENTS AND METHODS

Forty-three patients with histologically proven vasculitis (21 with Wegener's granulomatosis, 17 with microscopic polyangiitis, and 5 with renal-limited vasculitis) were studied for a median follow-up of 22 months. Disease activity was prospectively assessed and quantified by the Birmingham Vasculitis Activity Score. A total of 347 sera were analyzed for ANCA determination.

RESULTS

Relapses occurred in 23 (54%) of 43 patients. Diagnostic category (Wegener's granulomatosis vs micropolyangiitis and renal-limited vasculitis), severity of initial symptoms (mean vasculitis activity score, mean number of organs involved), and ANCA pattern [cytoplasmic-ANCA (c-ANCA) vs perinuclear-ANCA (p-ANCA)] did not significantly differ between relapsers and nonrelapsers. Lung involvement was more frequent at onset among relapsers [16 of 23 (70%) vs 6 of 20 (30%); P = 0.02]. Relapses were slightly, but not significantly, more frequent in patients with Wegener's granulomatosis or a c-ANCA pattern. The percentage of relapsers was greater in patients with persistently positive ANCA than in patients with negative or decreasing ANCA titers (86% vs 20%, P = 0.0001). However, the predictive value of an increase in ANCA titers for the occurrence of a subsequent relapse was only 28% (4 of 14) for c-ANCA, 12% (2 of 17) for anti-proteinase 3-ANCA, and 43% (6 of 14) for anti-myeloperoxidase-ANCA. An increase in ANCA occurred before or during relapse in 33% (10 of 30) of cases for c-ANCA/anti-proteinase 3 antibodies, and 73% (11 of 15) of cases for anti-myeloperoxidase antibodies.

CONCLUSION

The persistence of ANCA positivity is strongly associated with relapses. However, an increase in ANCA titers has a poor value for the early prediction of a subsequent relapse and should not be used as a sole parameter for therapeutic intervention. In addition, our results suggest that serial anti-myeloperoxidase determination may be useful as a prognostic marker in patients who are p-ANCA positive.

Microscopic polyangiitis: clinical and laboratory findings in eighty-five patients

OBJECTIVE

To retrospectively analyze the clinical symptoms, laboratory findings, and outcomes in patients with microscopic polyangiitis (MPA) who were enrolled in various clinical trials conducted by the French Vasculitis Study Group.

METHODS

A cohort of 85 patients meeting the Chapel Hill criteria for MPA participated in the study. Seventy-one of them were included in prospective therapeutic trials. Eighty-one diagnoses were biopsy proven. In the other patients, diagnosis was based on clinical findings.

RESULTS

Forty-seven men and 38 women, with a mean +/- SD age of 56.8 +/- 14.6 years, met the criteria for MPA. Their main clinical symptoms were renal manifestations (78.8%), weight loss (72.9%), skin involvement (62.4%), fever (55.3%), mononeuritis multiplex (57.6%), arthralgias (50.6%), myalgias (48.2%), hypertension (34.1%), lung involvement (24.7%; alveolar hemorrhage 11.8%), and cardiac failure (17.6%). The mean +/- SD serum creatinine level before treatment was 2.59 +/- 2.96 mg/dl; 47 patients had renal insufficiency (serum creatinine > 1.36 mg/dl). Eight patients underwent dialysis at the time of diagnosis, and long-term dialysis was necessary for 10 patients. Antineutrophil cytoplasmic antibodies (ANCA) were present in 38 of 51 patients (74.5%), of whom 33 had a perinuclear staining pattern (pANCA) and 5 had a cytoplasmic pattern. Antibodies to proteinase 3 were present in 4 patients and antibodies to myeloperoxidase were detected in 31, as determined by enzyme-linked immunosorbent assay. Of the 30 patients who underwent renal and celiac angiography, 4 had microaneurysms. Of the 29 patients (34.1%) who had relapses, 8 died during or after the relapse. During followup, 28 of the 85 patients (32.9%) died. The mean +/- SD duration of followup of the group was 69.9 +/- 60.6 months. Deaths were less frequent when patients had been treated with steroids and immunosuppressive drugs (13 patients [24.1%]) than with steroids alone (15 patients [48.4%]) (P < 0.01). The 5-year survival rate was 74%.

CONCLUSION

This study demonstrated that MPA is a multisystemic disease in which renal symptoms are frequent, but the disease is also associated with general symptoms, arthritis, mononeuritis multiplex, and other manifestations that are also seen in various vasculitides. The rarity of abnormal angiogram findings and the high frequency of pANCA are characteristic of MPA. In most cases, the outcome is comparable with those of other systemic vasculitides, but relapses are frequent.

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.

Evolving concepts about the role of antineutrophil cytoplasm autoantibodies in systemic vasculitides

This review discusses the main issues of antineutrophil cytoplasm autoantibodies (ANCA) that have emerged from the literature. From January 1997 to August 1998, 216 papers were published on ANCA. Two major themes seem to be evolving from these articles. The first theme concerns the specificity and sensitivity of ANCA testing in clinical practice in relation to diagnosing systemic vasculitic syndromes. We focus on immunofluorescence patterns, ANCA antigens, testing methodology, and the (predictive) value of ANCA in clinical practice. Second, there is the unsolved question of how ANCA are etiologically involved in the development of the vasculitic lesion. Ongoing research questions the role of ANCA in stimulating granulocytes, monocytes, and the endothelium.

Pulmonary vasculitis

Pulmonary vascular inflammation may be seen in a variety of primary lung diseases and in the setting of numerous systemic illnesses. This article reviews those entities in which pulmonary vasculitis represents a central feature of the pathologic process (Wegener's granulomatosis, Churg-Strauss syndrome, and pulmonary capillaritis). In addition, features of pulmonary involvement in other systemic vasculitides (Giant Cell Arteritis, Takayasu's Arteritis, and Behçet's disease) are described. Finally, general principles for the treatment of vasculitis are reviewed.

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.

A simple high yield procedure for purification of human proteinase 3, the main molecular target of cANCA

Proteinase 3, the antigen commonly recognized by classical anti-neutrophil cytoplasmic antibodies (cANCA) in patients with Wegener's granulomatosis was purified from neutrophil azurophilic granules. Proteinase 3, a serine protease with an apparent molecular mass of 29 kDa, was extracted with Triton X-100 from the azurophilic granule fraction of neutrophils after nitrogen bomb cavitation and Percoll gradient centrifugation. Anion exchange chromatography removed many proteins, which were bound to the column. The unbound proteins, which contained most of the proteinase 3, were then separated by gel filtration. All chromatography steps were done in the presence of detergent. SDS polyacrylamide gel electrophoresis of this preparation only revealed three bands migrating closely together at the position of a 29-31 kDa protein, characteristic of proteinase 3. Affinity-purified polyclonal antibodies raised against proteinase 3 were used for immunoblotting studies and demonstrated that the purified protein was proteinase 3. Antibodies to elastase, cathepsin G, myeloperoxidase, lactoferrin or lysozyme did not react in ELISA assays with the isolated protein. The proteinase 3 prepared by this procedure was found to be suitable as an antigen for detecting PR3-ANCA both in ELISA and in immunoblotting experiments.