ANTINEUTROPHIL CYTOPLASMIC AUTOANTIBODY TESTING IN VASCULITIDES

Granulomatous Sarcoidosis Mimics

Many granulomatous diseases can mimic sarcoidosis histologically and in terms of their clinical features. These mimics include infectious granulomatous diseases, granulomatous reactions to occupational and environmental exposures, granulomatous drug reactions, vasculitides and idiopathic granulomatous conditions. It is important to distinguish sarcoidosis from these mimics, as a misdiagnosis of these diseases may have serious consequences. This manuscript reviews numerous sarcoidosis mimics and describes features of these diseases that may allow them to be differentiated from sarcoidosis. Distinguishing features between sarcoidosis and its mimics requires a careful review of the medical history, symptoms, demographics, radiographic findings, histologic features, and additional laboratory data. Understanding the clinical characteristics of sarcoidosis and its mimics should lead to more accurate diagnoses and treatment of granulomatous disorders that should improve the care of these patients. As the diagnostic criteria of sarcoidosis are not standardized, it is possible that some of these sarcoidosis mimics may represent varied clinical presentations of sarcoidosis itself.

Small vessel vasculitis of the lung

Interstitial Lung Disease Program, National Jewish Medical and Research Center, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA The diagnosis and management of SVV remains one of the most challenging clinical scenarios encountered by a clinician. Careful attention to detail and a thorough knowledge of the specific disorders, their therapies, and complications thereof is required to optimally care for these patients. The recent completion of a number of randomized, controlled, multicenter clinical trials has greatly improved our knowledge base and ability to care for vasculitis patient. The next decade holds even more promise.

Upper Gastrointestinal Bleeding as the First Manifestation of Wegener's Granulomatosis

Wegener’s granulomatosis is an uncommon inflammatory disease that manifests as vasculitis, granulomatosis, and necrosis. It usually involves the upper and lower respiratory tracts and kidneys. Although it may essentially involve any organ, gastrointestinal (GI) involvement is notably uncommon.

A 20-year-old male patient presented with epigastric pain, vomiting, hematemesis, and melena. On physical examination, he was pale. There was no abdominal tenderness or organomegaly. Upper GI endoscopy revealed dark blue-colored infiltrative lesions in prepyloric area. Evaluation of the biopsy sample showed mononuclear cell infiltration in the submucosal area, hyperplastic polyp, and chronic gastritis. High dose proton pump inhibitor and adjunctive supportive measures were given but no change in the follow-up endoscopy was detected. During hospital course, he developed intermittent fever and serum creatinine elevation. 12 days after admission, he developed dyspnea, tachypnea, and painful swelling of metacarpophalangeal joints, and maculopapular rash in extensor surface of the right forearm. Chest radiography showed pulmonary infiltration. Serum c-ANCA titer was strongly positive and skin biopsy revealed leukocytoclastic vasculitis. The patient received methylprednisolone pulse, which resulted in complete recovery of symptoms and gastric lesion.

The present case indicates that GI bleeding may be the first manifestation of Wegener’s granulomatosis. Moreover, it should be emphasized that gastric biopsy is not characteristic or diagnostic in such patients.

Clinical Features of Neuropsychiatric Syndromes in Systemic Lupus Erythematosus and Other Connective Tissue Diseases

Systemic lupus erythematosus (SLE) and related disorders are chronic inflammatory diseases characterized by abnormalities and, in some cases, even complete failure of immune responses as the underlying pathology. Although almost all connective tissue diseases and related disorders can be complicated by various neuropsychiatric syndromes, SLE is a typical connective tissue disease that can cause neurological and psychiatric syndromes. In this review, neuropsychiatric syndromes complicating connective tissue diseases, especially SLE are outlined, and pathological and other conditions that should be considered in the differential diagnosis are also discussed.

A novel autoantibody against moesin in the serum of patients with MPO-ANCA-associated vasculitis

BACKGROUND

Antineutrophil cytoplasmic autoantibody (ANCA) directed against myeloperoxidase (MPO), a diagnostic criterion in MPO-ANCA-associated vasculitis (MPO-AAV), does not always correlate with disease activity. Here, we detected autoantibodies against moesin, which was located on the surface of stimulated endothelial cells, in the serum of patients.

METHODS

The anti-moesin autoantibody titer was evaluated by ELISA. Seventeen kinds of cytokines/chemokines were measured by a Bio-Plex system.

RESULTS

Serum creatinine in the anti-moesin autoantibody-positive group was higher than that in the negative group. Additionally, interferon (IFN)-γ, macrophage chemotactic peptide-1 (MCP-1), interleukin (IL)-2, IL-7, IL-12p70, IL-13, granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor were significantly higher in the positive group. Furthermore, IL-7 and IL-12p70 levels correlated with the anti-moesin autoantibody titer. Based on these findings and the binding of anti-moesin IgG to neutrophils and monocytes, we detected the secretion of cytokines/chemokines such as IFN-γ, MCP-1 and GM-CSF from these cells.

CONCLUSIONS

The anti-moesin autoantibody existed in the serum of patients with MPO-AAV and was associated with the production of inflammatory cytokines/chemokines targeting neutrophils with a cytoplasmic profile, which suggests that the anti-moesin autoantibody has the possibility to be a novel autoantibody developing vasculitis via neutrophil and endothelial cell activation.

Perinuclear antineutrophil cytoplasmic autoantibodies in dogs infected with various vector-borne pathogens and in dogs with immune-mediated hemolytic anemia

OBJECTIVE

To determine the prevalence of perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) in dogs with confirmed or suspected immune-mediated hemolytic anemia (IMHA) or dogs infected with various vector-borne pathogens, including Rickettsia rickettsii, Bartonella henselae, Bartonella vinsonii subsp berkhoffii, Ehrlichia canis, Borrelia burgdorferi, and Leishmania infantum.

ANIMALS

55 dogs with confirmed or suspected IMHA, 140 dogs seroreactive for vector-borne pathogens, and 62 healthy dogs and dogs seronegative for vector-borne pathogens.

PROCEDURES

Samples were allocated to subgroups on the basis of the health status of the dogs and the degree of seroreactivity against various vector-borne pathogens. Serum samples were tested retrospectively via indirect immunofluorescence assay to determine pANCA status.

RESULTS

26 of 55 (47%) dogs with confirmed or suspected IMHA and 67 of 140 (48%) dogs seroreactive for vector-borne pathogens had positive results when tested for pANCA. Serum samples with the highest antibody concentrations against L infantum antigen had the highest proportion (28/43 [65%]) that were positive for pANCA. One of 20 (5%) dogs seronegative for tick-borne pathogens and 8 of 22 (36%) dogs seronegative for L infantum had positive results for pANCA. One of 20 (5%) healthy dogs had serum antibodies against pANCA.

CONCLUSIONS AND CLINICAL RELEVANCE

pANCA were detected in a high percentage of dogs with IMHA and vector-borne infectious diseases. Therefore, pANCA may be a relatively nonspecific marker for dogs with inflammatory bowel disease, although they could represent a biomarker for immune-mediated diseases and infections.

Diagnosis and management of pulmonary vasculitis

The pulmonary vasculitides are a heterogeneous group of disorders characterized pathologically by vascular destruction with cellular inflammation and necrosis. These disorders can affect small, medium, and large vessels and may be primary or occur secondary to a variety of conditions. Vasculitis involving the lungs is most commonly due to primary, idiopathic, small-vessel antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides, which includes granulomatosis with polyangiitis (formerly Wegener’s granulomatosis), Churg–Strauss syndrome, and microscopic polyangiitis. From a clinical perspective these remain among the most challenging of diseases both in terms of diagnosis and treatment. This review will focus on diagnosis and management of ANCA-associated vasculitides.

Current modalities in the diagnosis of pulmonary vasculitis

INTRODUCTION

This review addresses the pulmonary manifestations of the vasculitides, with a focus on diagnostic modalities. Haemorrhagic presentations (usually associated with nephritis: the pulmonary-renal syndrome) are the most common vasculitic cause of early death.

AREAS COVERED

The diagnostic modalities in the pulmonary vasculitides are reviewed, with a focus on primary systemic vasculitis. A literature search of original research and review articles on pulmonary vasculitides was undertaken using the PubMed database.

EXPERT OPINION

Small-vessel anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, especially granulomatosis with polyangiitis (Wegener's granulomatosis) are the most frequent causes of pulmonary vasculitis and typically present as nodules, alveolar infiltrates (haemorrhagic or not), cavities or tracheobronchial stenosis. Lung involvement is less common in large-vessel vasculitis when pulmonary vascular abnormalities can be seen. No single test is pathogonomonic and diagnosis requires integration of clinical, laboratory, imaging and histological findings. Treatment follows similar regimens to other vasculitic presentations, with glucocorticoids in conjunction with immunosuppressive agents, and management of intercurrent sepsis and the increased risk of cardiovascular and thromboembolic events. Prompt diagnosis and intensive treatment of pulmonary vasculitis is essential to improve early mortality and long-term outcomes.

The pulmonary vasculitides

The pulmonary vasculitides are a rare group of heterogeneous disorders unified by the histopathologic finding of inflammation and destruction of the blood vessel wall. Diagnosis of these disorders is exceptionally challenging, given their highly variable clinical presentation, their relative rarity, and the overlap of the signs and symptoms of vasculitis with much more common entities. However, advances in the management of vasculitis allow for accurate diagnosis, risk stratification in the individual patient, and the implementation of evidence-based, effective pharmacologic therapies. This concise clinical review addresses the diagnosis and management of the patient with pulmonary vasculitis and provides an up-to-date review of the state of the field.

Update in the Diagnosis and Management of Pulmonary Vasculitis

The term vasculitis encompasses a number of distinct clinicopathologic disease entities, each of which is characterized pathologically by cellular inflammation and destruction of the blood vessel wall, and clinically by the types and locations of the affected vessels. While multiple classification schemes have been proposed to categorize and simplify the approach to these diseases, ultimately their diagnosis rests on the identification of particular patterns of clinical, radiologic, laboratory, and pathologic features. While lung involvement is most commonly seen with the primary idiopathic, small-vessel or antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides of Wegener granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome, one should remember that medium-vessel vasculitis (ie, classic polyarteritis nodosa), large-vessel vasculitis (ie, Takayasu arteritis), primary immune complex-mediated vasculitis (ie, Goodpasture syndrome), and secondary vasculitis (ie, systemic lupus erythematosus) can all affect the lung. However, for the purpose of this review, we will focus on the ANCA-associated vasculitides.

The Clinical Spectrum of Primary Renal Vasculitis

BACKGROUND AND OBJECTIVES

The vasculitides are potentially severe and often difficult to diagnose syndromes. Many forms of vasculitis may involve the kidneys. This review will focus on the clinical and histopathological aspects of renal involvement in the systemic vasculitides.

METHODS

We searched the MEDLINE database using as key terms the MeSH terms and textwords for different forms of vasculitis and for renal involvement, creating a database of more than 2200 relevant references.

RESULTS

The frequency of renal involvement in vasculitis varies among different syndromes. It is more frequent in Wegener's granulomatosis and microscopic polyarteritis, while it is uncommon to rare in other forms of vasculitis such as Behçet's disease and relapsing polychondritis. The vessels affected include the renal artery in Takayasu arteritis, medium-size renal parenchymal artery in classic polyarteritis nodosa, and glomerular involvement in Wegener's granulomatosis and microscopic polyarteritis. The clinical expression of renal vasculitis depends on the size of the affected vessels and includes renovascular hypertension, isolated nonnephrotic proteinuria, interstitial nephritis, and glomerulonephritis, which can be rapidly progressive. Diagnosis is established by a combination of history, clinical manifestations, laboratory findings (eg, urine sediment, urine protein, antineutrophil cytoplasmic antibodies), imaging techniques (renal angiography, especially when there is a suspicion of medium-to-large vessel disease, and chest radiograph), and finally, renal biopsy. Prognosis varies from unfavorable in the rapidly progressive glomerulonephritis of microscopic polyarteritis, which can lead to renal failure, chronic dialysis, and renal transplantation, to benign, as in the case of Henoch Schonlein purpura, in which the majority of patients recover.

CONCLUSIONS

The manifestations and prognosis of renal vasculitis range widely. Renal involvement greatly influences prognosis and dictates the need for early and prompt immunosuppressive therapy. Thus, the clinician should be alert for the timely diagnosis and treatment of renal vasculitis.

Primary angiitis of the central nervous system: report of five biopsy-confirmed cases from Colombia

INTRODUCTION

Primary (isolated) angiitis of the central nervous system (PACNS) is a rare cause of cerebrovascular disease (CVD), and few leptomeningeal and brain biopsy (LBB)-confirmed cases have been reported from South America.

METHODS

We retrospectively reviewed charts of patients with diagnosis of cerebral angiitis admitted between March 1991 and July 2001 to a single university hospital in Medellin, Colombia. Patients with definitive diagnosis of PACNS by Alrawi et al.'s LBB criteria were selected. We excluded other causes of cerebral angiitis as well as cases without LBB confirmation.

RESULTS

We report five patients, four men and one woman, with a mean age at onset of 24.4 years, and an average disease progression of 12.4 days. Four presented with headache and motor weakness, three had seizures, and two had alterations of consciousness. Cerebral MRI was abnormal in all five cases; brain CT in four, and cerebral angiography in two. The cerebrospinal fluid (CSF) was abnormal in two patients. Leptomeningeal and brain biopsies revealed mononuclear infiltration in the wall of small blood vessels in all. Three had concurrent meningeal and cerebral involvement, two had necrotizing angiitis, and one had vascular and encephalitic lesions. All received only steroid treatment; the 1-year follow-up revealed good prognosis without relapses.

CONCLUSION

We report five biopsy-proven cases of PACNS from Colombia associated with neurological and neuroimaging abnormalities; these patients presented a mild inflammatory disease that was correlated with few CSF abnormalities and good response to single steroid treatment without relapses. Leptomeningeal and brain biopsy is mandatory for a definitive diagnosis.

Evaluation of assays for perinuclear antineutrophilic cytoplasmic antibodies and antibodies to Saccharomyces cerevisiae in dogs with inflammatory bowel disease

OBJECTIVE

To evaluate the use of immunofluorescence asssays for perinuclear antineutrophilic cytoplasmic antibodies (pANCAs) and antibodies to Saccharomyces cerevisiae (ASCAs) in dogs with inflammatory bowel disease (IBD) and assess the clinical value of these serologic markers of the disease.

ANIMALS

39 dogs with IBD, 18 dogs with acute diarrhea, 19 dogs with chronic non-IBD-associated diarrhea, 26 healthy dogs of various breeds and age, and 22 healthy young working dogs.

PROCEDURE

Sera obtained from the dogs in each group were added to canine granulocyte- and Saccharomyces cerevisiae-mounted slides for detection of pANCAs and ASCAs via immunofluorescence techniques. Sensitivity and specificity (with 95% confidence intervals [CIs]) were calculated for the group of dogs with IBD versus each of the 2 groups of healthy dogs, the group of dogs with acute diarrhea, and the group of dogs with chronic non-IBD-associated diarrhea.

RESULTS

Among the 39 dogs with IBD, 20 yielded positive results via the pANCA assay (sensitivity, 0.51 [95% CI, 0.35 to 0.67]) and 17 yielded positive results via the ASCA assay (sensitivity, 0.44 [95% CI, 0.22 to 0.69]). The specificity of the pANCA assay in the 4 groups of non-IBD-affected dogs ranged from 0.83 (95% CI, 0.85 to 0.96) to 0.95 (95% CI, 0.72 to 1.00).

CONCLUSIONS AND CLINICAL RELEVANCE

Immunofluorescence assays for pANCA and ASCA appear to be useful for the detection of IBD in dogs. The pANCA immunofluorescence assay had high specificity for canine IBD, and pANCAs appear to be accurate markers of intestinal inflammation.

Vasculitis: Wegener granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, polyarteritis nodosa, and Takayasu arteritis

Identification, diagnosis, and management of the primary vasculitides and their attendant complications is a challenging task for the critical care physician. However, with appropriate therapy, the morbidity and mortality of these diseases can be markedly improved and allow the individual patient to return to their previous functional state.

Evaluation and treatment of vasculitis in the critically ill patient

The systemic vasculitides, if left untreated, often lead to major organ damage and death. When a patient presents with features that may be consistent with vasculitis, especially with pulmonary and renal findings, it is important to make a specific diagnosis as quickly as possible so that specific therapy can be started. Diagnosis is dependent on familiarity with the myriad of typical and unusual clinical features of the various vasculitides together with performance of supportive tests including serologies, angiograms, and biopsies. When evaluating a potential case of vasculitis, clinicians must comprehensively search for other more common, non-vasculitic diseases. The diagnosis may be even more difficult in patients with established diagnoses of vasculitis on immunosuppressive treatment who develop new clinical findings. Rapid initiation of immunosuppressive therapy for critically ill patients with vasculitis is crucial and may be life-saving.

Differential diagnosis in nephropathology: an immunofluorescence-driven approach

Evaluation of a renal biopsy can be intimidating, because observational data from histologic stains, direct immunofluorescence (IF), and electron microscopy must be integrated with clinical and laboratory data to arrive at the correct diagnosis. Numerous diagnostic categories usually merit consideration. The typical strategy to diagnose renal disease is heavily weighted toward analysis of the histologic pattern of glomerular injury. This focus on histology is understandable; histologic evaluation was the first analytic probe available and has driven the formulation of classification schemes. Evaluation of IF before review of the light microscopy facilitates diagnostic evaluation, because the possibilities are immediately reduced. This simplifies the crucial final step-clinical and histologic correlation. In this review, I discuss the information content of IF and provide an algorithmic approach to the major renal diseases based on an IF-driven dissection of the differential diagnosis.

Epidemiology of the vasculitides

In summary, systemic vasculitides constitute a heterogeneous group of overlapping diseases that are somewhat more common than previously considered. Although the causes of vasculitis are largely unknown, epidemiologic studies have implicated geographic, genetic, and environmental factors. Ethnicity, various genes such as those of the MHC, gender, and environmental factors seem to account for the different incidence rates of these syndromes. GCA is the most common vasculitis in elderly people from Western countries. Small-sized cutaneous vasculitides, particularly HSP in children and HV in adults, are also common diseases. Increased physician awareness and the routine use of ANCA tests may contribute to an increase in the recognition of conditions such as WG and MPA.

Drug-induced vasculitis

DIV is a relatively common cause of inflammatory vasculitis. Drugs from almost every pharmacologic class have been implicated in causing vasculitis in sporadic cases. The level of certainty and quality of evidence for these associations between specific agents and vasculitis vary greatly. The clinical manifestations of DIV range from single organ involvement (most commonly, skin) to life-threatening multiorgan disease. The recently described subset of cases of DIV associated with positive tests for ANCA are an interesting subset of DIV. The diagnosis of DIV is usually one of exclusion. The treatment of DIV is dependent on the severity of disease activity but should always include withdrawal of the suspected drug. If no agent can be implicated, as many drugs as feasible should be discontinued. The necessity of prescribing glucocorticoids or immunosuppressive agents depends on the disease severity and other case-specific information. Increasing understanding of the pathophysiologic characteristics of all inflammatory vasculitides should lead to better diagnostic and therapeutic approaches to DIV.

Neutrophil functions of patients with vasculitis related to myeloperoxidase-specific anti-neutrophil antibody

Neutrophils are hypothesized to cause tissue damage resulting in the development of vasculitis and glomerulonephritis, although they are known to primarily take part in host defense functions. The infiltration of inflammatory cells. notably neutrophils and macrophages, is observed in the progression of vasculitis. Neutrophils with activated status and anti-neutrophil cytoplasmic antibodies (ANCAs), especially myeloperoxidase-specific (MPO)-ANCA, have been implicated in the development of vasculitis. The target molecule of MPG-ANCA is a lysosomal enzyme MPO that usually acts to kill bacteria, viruses, and fungi and that causes damage to the tissue due to the toxicity of its product, hypochlorite (OCl-). To elucidate the role of MPO-ANCA in the progression of vasculitis, a set of MPO-peptide fragments has been developed, and the corresponding epitope site for the specific monoclonal and/or oligoclonal antibody resulting in vasculitis has been determined. Recently some mouse models have been used for analyzing the correlation between MPO and MPO-ANCA in relation to damage of blood vessels followed by the development of vasculitis. This review focuses on the role of activated neutrophils in the development of vasculitis associated with MPO-ANCA and the target molecules of ANCA. In addition, the reactivities of ANCA and inflammatory cytokines involving leukocyte-derived chemotaxin 2 (LECT2) are also discussed.

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.

Wegener granulomatosis

Wegener granulomatosis (WG) is a necrotizing, granulomatous vasculitis that has a clinical predilection to involve the upper airways, lungs, and kidneys. Although the first case was reported by Klinger in 1931, Friedrich Wegener in 1936 characterized the unique clinical and pathological features of this disease that subsequently came to bear his name. Vascular inflammation and occlusion leading to tissue ischemia is a hallmark of WG. Although strong evidence indicates that such blood vessel damage is immunologically mediated, the mechanisms that initiate this process are still largely unknown. To date, there has been no clearly established association with genetic factors, specific infectious agents, or environmental irritants, although speculation has remained that these may play a role in triggering the onset of disease. Until the introduction of therapy with cyclophosphamide (CYC) and glucocorticoids, WG was uniformly fatal. Although drug toxicity and disease relapse remain of concern with this regimen, it has provided us with a successful means of treatment and the opportunity to better understand this disease through long-term patient follow-up.

Pauci-immune ANCA-positive crescentic glomerulonephritis associated with metastatic adenocarcinoma of the lung

A 66-year-old woman developed rapidly progressive renal failure several days after she was diagnosed with non-small cell carcinoma of the lung. Antineutrophil cytoplasmic antibody test performed as an indirect immunofluorescence assay was positive with a perinuclear pattern of staining (pANCA). The patient did not improve with hemodialysis treatment and died on the second day after admission to the hospital. A complete autopsy was performed and showed metastatic adenocarcinoma of the lung and pauci-immune crescentic glomerulonephritis. A literature search showed only 7 previously reported cases of malignant tumors associated with ANCA-positive pauci-immune crescentic glomerulonephritis. The clinicopathologic findings of the current and all previously reported cases and possible relationship between ANCA-positive glomerulonephritis and malignancy are discussed.

Isolated abdominal vasculitis as an atypical presentation of Wegener's granulomatosis

Although current classifications characterize vasculitic syndromes based upon the size of the vessels involved, the histopathology, and the presence or absence of antineutrophil cytoplasmatic antibodies ANCA (1-3), those occasional patients with vasculitis whose features are not typical may evade diagnosis and effective treatment. We report one such patient who presented with bilateral refractory uveitis and abdominal angina who had a positive C-ANCA. Because of his atypical presentation, this patient's disease progressed over 8 yr despite an extensive gastrointestinal evaluation, before a diagnosis of vasculitis was established angiographically, and immunosuppressive therapy was begun.

Comparative effects of antilactoferrin antibodies and tumor necrosis factor on neutrophil adherence to matrix proteins

Neutrophil adherence to matrix proteins likely plays an important role in inflammatory responses. Antineutrophil cytoplasm antibodies may activate neutrophils in certain diseases. Using an in vitro method that allows simultaneous quantitation of neutrophil adherence and superoxide secretion, we compared the effects of antibodies against neutrophil granule proteins and tumor necrosis factor alpha (TNF-alpha), a known neutrophil agonist. Antilactoferrin antibodies but not antielastase or antimyeloperoxidase antibodies stimulated increased adherence to fibronectin and laminin similar in degree to that induced by TNF-alpha. This, but not the simultaneous superoxide secretion, was inhibited in the presence of anti-CD18 antibodies. Humoral immune responses to lactoferrin, likely expressed on the neutrophil surface, can activate neutrophils in proinflammatory responses that may be pathogenic.

Antineutrophil Cytoplasmic Antibodies Preferentially Engage FcγRIIIb on Human Neutrophils

Antineutrophil cytoplasmic Abs (ANCA) are found in the circulation of many patients with systemic vasculitis. ANCA bind to ANCA target, such as proteinase 3 and myeloperoxidase, and activate neutrophils in an FcγR-dependent manner. Human neutrophils constitutively express FcγRIIa (CD32) and FcγRIIIb (CD16), and there is clear in vitro experimental evidence of ANCA-mediated engagement of FcγRIIa. However, direct experimental evidence of ANCA engagement of neutrophil FcγRIIIb has been obscured by technical problems related to activation-induced receptor shedding and activation-induced expression of receptor on the surface of neutrophils. In this study, by blocking receptor shedding and using appropriate reporter anti-FcγR mAb, we show that human cANCA and pANCA, and murine mAb with corresponding reactivities, can indeed engage FcγRIIIb. Furthermore, our data suggest that FcγRIIIb is preferentially engaged by ANCA relative to FcγRIIa presumably due to the nearly 10-fold excess of FcγRIIIb expression relative to FcγRIIa expression. These results clearly demonstrate that the Fc region of ANCA bound to an ANCA target on the neutrophil surface engage FcγRIIIb and indicate that FcγRIIIb and FcγRIIa may both be active participants in ANCA-induced neutrophil activation. However, given the low levels of ANCA target expression on neutrophils from patients with systemic vasculitis, FcγRIIIb is likely to play a critical role in initiating and perpetuating ANCA-induced neutrophil activation.

Genetic Determinants of Autoimmune Disease and Coronary Vasculitis in the MRL-lpr/lpr Mouse Model of Systemic Lupus Erythematosus

MRL-lpr/lpr (MRL/lpr) mice are a model of human autoimmune disease. They exhibit a number of characteristics of systemic lupus erythematosus, including anti-DNA Abs, anti-cardiolipin Abs, immune complex-mediated vasculitis, lymphadenopathy, and severe glomerulonephritis. Although the autoimmune disorder is mediated primarily by mutation of the Fas gene (lpr), which interferes with lymphocyte apoptosis, MRL/lpr mice also have other predisposing genetic factors. In an effort to identify these additional factors, we have applied quantitative trait locus (QTL) mapping using an intercross between MRL/lpr mice and the nonautoimmune inbred strain BALB/cJ. A complete linkage map spanning the entire genome was constructed for 189 intercross progeny, and genetic loci contributing to features of the autoimmunity were identified using statistical analytic procedures. As expected, the primary genetic determinant of autoimmune disease in this cross was the Fas gene on mouse chromosome 19, exhibiting a lod score of 60. In addition, two novel loci, one on chromosome 2 (lod score, 4.3) and one on chromosome 11 (lod score, 3.1), were found to contribute to levels of anti-DNA Abs. Interestingly, the chromosome 19 and chromosome 11 QTLs, but not the chromosome 2 QTL, also exhibited associations with anti-cardiolipin Abs (lod scores, 38.4 and 2.6). We further examined the effects of these QTLs on the development of coronary vasculitis in the F2 mice. Our results indicate that the QTLs on chromosomes 11 and 19 also control the development of vasculitis, demonstrating common genetic determinants of autoantibody levels and vasculitis.

Diagnostic approach to central and peripheral nervous system vasculitis

The diagnosis of vasculitis is first and foremost a clinical one. Correct diagnosis requires a high index of suspicion coupled with knowledge of the manifestations of other disorders that may masquerade as vasculitis. Treatment of vasculitis requires prolonged use of drugs with the potential for serious side effects. Whereas the prompt initiation of definitive treatment is a very high priority, there is also substantial risk of inappropriately treating self-limited and more benign disorders mimicking vasculitis. This has been a particular problem with primary angiitis of the central nervous system. Laboratory studies, particularly tissue biopsy, provide a crucial adjunct to clinical diagnosis.

Treatment of antineutrophil cytoplasm autoantibody-associated systemic vasculitis: initiatives of the European Community Systemic Vasculitis Clinical Trials Study Group

The diagnosis, treatment, and monitoring of the primary systemic vasculitides associated with circulating antineutrophil cytoplasm autoantibodies (ANCA) have formed the focus of a multicenter collaborative study. Consensus has been reached on criteria for classification, clinical subgroupings by extent and severity of disease, and "standard" and "best alternative" therapeutic regimens. Two series of randomized controlled trials have been designed; their aims are (1) to harmonize current approaches to treatment and (2) to test the value of newer therapeutic agents. In support of these trials, semiobjective scoring systems have been created and validated, and previous standardization of ANCA serologic and histologic analysis has been adopted. The systems of classification and clinical management described herein represent the recommendations of a multidisciplinary study group that hopes to improve the outcome of patients with primary systemic vasculitis by wide dissemination of the collective experience from interested centers.

Diagnosis and treatment of the systemic and cutaneous necrotizing vasculitis syndromes

Advances in understanding of the spectrum of clinical presentations of patients with systemic and cutaneous necrotizing vasculitis as well as further work on pathogenesis of these conditions has helped with diagnosis of these conditions. Therapies for systemic and cutaneous necrotizing vasculitis are based on disease extent, severity, and concomitant conditions in the individual patient. Future multicenter and multidisciplinary studies will provide improved treatments for these challenging clinical situations.

Pathogenesis of vasculitis syndromes

The pathogenesis of vasculitis is complex and involves a variety of mechanisms acting in concert to bring about necrotizing inflammation of blood vessel walls. In recent years, there has been considerable progress in dissecting the immunologic abnormalities present in specific vasculitis syndromes. The primary immunopathogenic events that initiate the process of vascular inflammation and blood vessel damage, however, are still largely unknown. Although the cause of most vasculitis syndromes remains a mystery, advances in molecular and cellular immunology have defined many of the effector mechanisms that mediate inflammatory vascular damage. In this regard, modulation of the inflammatory response by specific cytokine and adhesion molecule antagonists is now possible and may prove beneficial in the treatment of vasculitis.