ANCA Associated with Behçet's Disease

Behçcet's disease is a multisystem disorder affecting primarily mucocutaneous and ocular sites although the gastrointestinal, cardiovascular, central nervous and respiratory systems may also be involved. Hulusi Behçet, a Turkish dermatologist, first described Behçet's disease in 1937 and suggested a possible infectious aetiology1. The pathogenesis of this condition still remains unclear although it is likely that infection acts as a trigger in genetically susceptible individuals.

We report a patient with unusual cutaneous manifestations of Behçet's disease and antineutrophil cytoplasmic antibodies (ANCA) directed against the cytotoxic protein, bactericidal/permeability-increasing protein (BPI). This is the first report of Behçet's disease associated with this autoantibody.

Regulation of Autoantibody Responses to Glomerular Basement Membrane in Man and Experimental Animals

Autoantibodies reacting with the glomerular basement membrane (GBM) are a rare cause of severe nephritis in man. Their development is HLA-DR-associated and their pathogenicity has been demonstrated by transfer experiments. Their production is spontaneously self-limiting over a period of years but irreversible renal failure usually occurs within weeks or months in the untreated patient. A regimen of intensive plasma exchange together with cytotoxic drugs and steroids induces a rapid and permanent arrest of antibody synthesis; this is associated with recovery of renal function, provided that target organ injury is not irreversible when treatment is initiated. To understand the homeostatic mechanisms engaged by the therapeutic regimen we have studied an experimental model of autoimmune nephritis in the Brown Norway rat, where autoantibody-mediated injury to the GBM is induced by mercuric chloride. Suppressor cells and humoral factors (putatively anti-idiotypic antibodies) were found to regulate autoantibody production, and cyclophosphamide can prevent its reinduction. To identify the autoantigenic component in human GBM we have produced a mouse monoclonal antibody which recognizes the same components as are recognized by autoantibodies from all 35 patients tested. This monoclonal antibody can be used to study the autoregulatory components from human blood which we have found to be important in the animal model.

The intermediate endpoint effect in logistic and probit regression

BACKGROUND

An intermediate endpoint is hypothesized to be in the middle of the causal sequence relating an independent variable to a dependent variable. The intermediate variable is also called a surrogate or mediating variable and the corresponding effect is called the mediated, surrogate endpoint, or intermediate endpoint effect. Clinical studies are often designed to change an intermediate or surrogate endpoint and through this intermediate change influence the ultimate endpoint. In many intermediate endpoint clinical studies the dependent variable is binary, and logistic or probit regression is used.

PURPOSE

The purpose of this study is to describe a limitation of a widely used approach to assessing intermediate endpoint effects and to propose an alternative method, based on products of coefficients, that yields more accurate results.

METHODS

The intermediate endpoint model for a binary outcome is described for a true binary outcome and for a dichotomization of a latent continuous outcome. Plots of true values and a simulation study are used to evaluate the different methods.

RESULTS

Distorted estimates of the intermediate endpoint effect and incorrect conclusions can result from the application of widely used methods to assess the intermediate endpoint effect. The same problem occurs for the proportion of an effect explained by an intermediate endpoint, which has been suggested as a useful measure for identifying intermediate endpoints. A solution to this problem is given based on the relationship between latent variable modeling and logistic or probit regression.

LIMITATIONS

More complicated intermediate variable models are not addressed in the study, although the methods described in the article can be extended to these more complicated models.

CONCLUSIONS

Researchers are encouraged to use an intermediate endpoint method based on the product of regression coefficients. A common method based on difference in coefficient methods can lead to distorted conclusions regarding the intermediate effect.

Specific immunoabsorption

Rapidly progressive glomerulonephritis occurs in patients developing autoantibodies to the glomerular basement membrane (GBM) and in multisystem vasculitic syndromes such as Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA). In anti-GBM disease the pathogenicity of the autoantibodies has been established by transfer experiments; new solid-phase radioimmunoassays (RIAs) for circulating autoantibodies allow early diagnosis and effective monitoring of treatment. Sequential measurements of antibody levels showed that their generation is self-limiting (even without treatment) and that their production can be arrested more quickly with immunosuppressive therapy (cyclophosphamide and high dose steroids) together with intensive plasma exchange. In systemic vasculitis, no pathogenic agent has been identified and the diseases are rarely self-remitting. In WG, antibodies to cytoplasmic components of normal human neutrophils (and monocytes) were reported to be detectable by indirect immunofluorescence, with titres correlating with disease activity. We confirmed this and showed that antigen can be extracted from normal human neutrophils and used as ligand in a solid-phase RIA. Sera from patients with other forms of systemic vasculitis, such as MPA, as well as WG, are positive in this assay. The antigens have been further characterized by HPLC fractionation on a Toyosoda TSK gel filtration column. In WG, antibodies were directed towards cytoplasmic fractions of 100, 6 and 2 kDa; in MPA, antibody reacted only with the 100 kDa fraction. These findings suggest a humoral pathogenesis in these disorders and indicate that this approach may be helpful in the classification, diagnosis and monitoring of therapy in the systemic vasculitides. Further characterization of the autoantigen and its potential use in specific immunoabsorption are discussed.

Remission induction in Behçet's disease following lymphocyte depletion by the anti-CD52 antibody CAMPATH 1-H

OBJECTIVE

Behçet's disease (BD) is a multisystem vasculopathy of unknown cause with variable clinical presentation and the outcome of current treatments is often unsatisfactory. There is evidence for T-cell autoreactivity in BD and this study explores the therapeutic response to lymphocyte depletion with a humanized anti-CD52 antibody, CAMPATH-1H.

METHODS

Eighteen patients with active BD received a single course of 134 mg of CAMPATH-1H. Immunosuppressives were withdrawn and prednisolone reduced according to clinical status. Treatment response was assessed by remission of clinical features of disease activity, erythrocyte sedimentation rate, C-reactive protein, prednisolone dose, the need for subsequent immunosuppressives and disease relapse.

RESULTS

By 6 months, 13/18 (72%) had entered remission and average, daily prednisolone dose was reduced from 17.7 to 6.7 mg/day (P < 0.005). At patient follow-up after 37 (6-60) months, seven had relapsed after an average of 25 months, five had required the introduction of an immunosuppressive drug and two had been retreated with CAMPATH-1H; 10 were in stable remission and six were receiving no therapy. Moderate infusion-related adverse effects occurred in five and two developed hypothyroidism. Circulating CD4+ T cells fell to low levels after CAMPATH-1H and remained depressed for at least 1 yr; no opportunistic infections were seen.

CONCLUSIONS

The therapeutic response to CAMPATH-1H suggests a central role for autoreactive lymphocytes in BD. The potential of CAMPATH-1H to induce sustained treatment-free remission in BD poorly controlled by conventional therapy requires further evaluation.

Epitope mapping on Wegener's granulomatosis autoantigen proteinase 3

OBJECTIVE

To map the epitopes on Wegener's granulomatosis autoantigen proteinase 3.

METHODS

Antigenicity of proteinase 3 was studied with Western blot analysis in which proteinase 3 was prepared under reducing and non-reducing conditions. Two anti-proteinase 3 monoclonal antibodies, HZ1F12 and HZ1H3, were used to inhibit each other and to inhibit 22 anti-proteinase 3 positive sera from patients with Wegener's granulomatosis in competitive inhibition enzyme-linked immunosorbent assays (ELISA) and Western blot analysis.

RESULTS

All monoclonal antibodies and patient sera recognized proteinase 3 under non-reducing conditions in Western blot analysis. ZH1F12 was inhibited 74% by HZ1H3. 10/22 (46%) sera were completely or partially inhibited by HZ1F12; 9/22 (41%) sera were partially inhibited by HZ1H3; and 6/22 (27%) were inhibited by both monoclonal antibodies. In inhibition Western blot analysis, the binding of patient sera to proteinase 3 could be inhibited by HZ1F12.

CONCLUSIONS

The epitopes of Wegener's granulomatosis autoantigen were conformational. Anti-proteinase 3 monoclonal HZ1F12 and HZ1H3 recognized similar or overlapping epitopes on the proteinase 3 molecule. Epitopes of proteinase 3 recognized by anti-proteinase 3 positive sera were not restricted.

Analysis of anti-neutrophil cytoplasmic antibodies (ANCA): frequency and specificity in a sample of 191 homozygous (PiZZ) alpha1-antitrypsin-deficient subjects

BACKGROUND

ANCA are autoantibodies directed against polymorphonuclear cell antigens, mainly proteinase 3 (PR3) and myeloperoxidase (MPO), which are implicated in the pathogenesis of small-vessel necrotizing vasculitis. Alpha1-antitrypsin is the main inhibitor of neutral serine proteinase [i.e. human leukocyte elastase (HLE) and PR3] present in PMN alpha-granules (alphaGr). An association first reported by us between PR3 ANCA and the deficient PiZZ phenotype in ANCA-positive systemic vasculitis, now widely confirmed by others, led us to study the incidence and specificity of ANCA among PiZZ subjects.

METHODS

We tested a population of 191 PiZZ (273 sera) for ANCA activity versus 272 PiMM matched control subjects using alphaGr or antigen-specific ELISA [PR3, HLE, MPO, lactoferin (LF) and bactericidal/ permeability increasing protein (BPI)].

RESULTS

The incidence of antibodies directed against alphaGr and HLE but not PR3, MPO, LF or BPI was increased in the PiZZ as compared to the PiMM group (Fisher probability respectively P < 0.0001 and P < 0.05).

CONCLUSIONS

ANCA not directed against classical antigens (MPO and PR3) may be found in PiZZ patients. However, these patients do not develop systemic vasculitis features. Therefore, alpha1-antitrypsin deficiency is not sufficient to induce ANCA positive vasculitides, and may only act as a second hit amplifying factor.

Equivalence of the mediation, confounding and suppression effect

This paper describes the statistical similarities among mediation, confounding, and suppression. Each is quantified by measuring the change in the relationship between an independent and a dependent variable after adding a third variable to the analysis. Mediation and confounding are identical statistically and can be distinguished only on conceptual grounds. Methods to determine the confidence intervals for confounding and suppression effects are proposed based on methods developed for mediated effects. Although the statistical estimation of effects and standard errors is the same, there are important conceptual differences among the three types of effects.

Intravenous immunoglobulin for ANCA-associated systemic vasculitis with persistent disease activity

Intravenous immunoglobulin (IVIg) is a potential alternative treatment for anti-neutrophil cytoplasm antibody (ANCA)-associated systemic vasculitis (AASV) with less toxicity than conventional immunosuppressive agents. This randomized, placebo-controlled trial aimed to investigate the efficacy of a single course of IVIg (total dose 2 g/kg) in previously-treated AASV with persistent disease activity in whom there was an intention to escalate therapy. Vasculitic activity was monitored by the Birmingham vasculitis activity score (BVAS), C-reactive protein (CRP) and ANCA levels. Treatment response was defined as a reduction in BVAS of more than 50% after 3 months, and there was an intention to keep doses of concurrent immunosuppressive drugs unchanged during this period; follow-up continued to 12 months. Seventeen patients were randomized to receive IVIg and 17 to receive placebo. Treatment responses were found in 14/17 and 6/17 of the IVIg and placebo groups, respectively (p=0.015, OR 8.56, 95%CI 1.74-42.2). Following infusion of trial medication, greater falls in CRP were seen at 2 weeks (p=0.02) and 1 month (p=0.04) in the IVIg group. No differences were observed between ANCA levels or cumulative exposure to immunosuppressive drugs, and after 3 months there were no differences in CRP levels or disease activity between the IVIg and placebo groups. Seventeen adverse effects occurred after IVIg and six after placebo: they were mostly mild, although reversible rises in serum creatinine occurred in four from the IVIg group. A single course of IVIg reduced disease activity in persistent AASV, but this effect was not maintained beyond 3 months; mild, reversible side-effects following IVIg were frequent. IVIg is an alternative treatment for AASV with persistent disease activity after standard therapy.

Anti-adhesion molecule therapy as an interventional strategy for autoimmune inflammation

Functional inactivation of leukocyte adhesion molecules has been used to intervene in the development of tissue injury in experimental models of postperfusion infarction as well as autoimmune inflammation. We investigated the use of humanized monoclonal antibodies (mAb) against CD18 in the treatment of five patients with vasculitic tissue injury sufficient to threaten infarction or gangrene. The treatment was monitored in three ways: (i) whole-body gamma camera scintiscanning of autologous indium-labeled PMN, (ii) an index of the therapeutic inhibition of adhesion derived from comparison pre, during, and post mAb treatment of the ability of patients' PMN to be aggregated after activation by fMLP, and (iii) flow cytometric analysis of PMN CD18 expression. Four of five patients given anti-CD18 at 20 mg/day for up to 3 weeks showed prompt clinical improvement, with healing of the ulceration and restoration of limb function within 4 weeks, which was sustained. The fifth patient, who was not doing well clinically, decided to withdraw from all active treatment: at autopsy there was no evidence of the underlying vasculitis evident pretreatment. Our findings suggest that anti-adhesion molecule treatment might be an effective immediate treatment in severe vasculitis especially when tissue viability is threatened by progressive infarction and/or development of gangrene.

Anti-neutrophil cytoplasmic antibodies (ANCA) against bactericidal/permeability-increasing protein (BPI) and cystic fibrosis lung disease

Persistent infection with Pseudomonas aeruginosa and inflammatory mechanisms play an important role in cystic fibrosis (CF) lung disease. ANCA against BPI, a potent host defence protein with anti-bacterial and anti-endotoxin properties, have been described in CF. We have assessed the relationship of anti-BPI antibodies to pulmonary disease severity in 148 CF subjects. IgA and IgG anti-BPI antibodies were found in 55.4% and 70.3% of CF patients, respectively, and higher levels were strongly associated with colonization with P. aeruginosa (P = 0.001 and 0.039 for IgA and IgG antibodies, respectively). IgA and IgG anti-BPI antibodies were independently associated with more severe lung disease as assessed by chest radiograph score (P = 0.023) and a significantly lower forced expiratory volume in 1 s (FEV1)% (P = 0.01). The pathophysiological relevance of the autoantibodies was investigated further by determining their epitope specificity and their effect on bacterial phagocytosis in vitro. Both isotypes of anti-BPI antibodies were specific for the C-terminus of BPI shown recently to be important for BPI-mediated opsonization, and in vitro affinity-purified anti-BPI antibodies significantly reduced BPI-induced phagocytosis of Escherichia coli compared with controls. These data indicate that anti-BPI autoantibodies are associated with colonization with P. aeruginosa and worse lung disease in CF. The inhibition of bacterial phagocytosis suggests that these autoantibodies may contribute to the persistence of P. aeruginosa in the CF lung and so play a role in perpetuating CF lung damage.

Heat treatment of normal human sera reveals antibodies to bactericidal permeability-inducing protein (BPI)

Heat treatment of normal sera to 56 degrees C for 30 min, a common procedure for the inactivation of viruses, e.g. HIV, reveals the presence of antibodies to neutrophil cytoplasm antigens (ANCA), as detected by indirect immunofluorescence on ethanol-fixed human neutrophils and by antigen-specific ELISA for BPI. Reactivity was not seen to the other common vasculitis-associated antigens proteinase 3 (PR3) or myeloperoxidase (MPO). The effect of temperature was maximal at 56 degrees C, with substantial antibody demonstrable after only 5 min at this temperature. In experiments using polyethylene glycol (PEG)6000 to remove immune complexes, the effect of heating could be abrogated by preincubation with 8% PEG, which suggested that these anti BPI antibodies might be complexed in sera. After passage of normal plasma over a protein G column, the acid-eluted fraction contained elevated levels of antibodies to BPI but not to other vasculitis-associated antigens such as PR3 or MPO, nor to glomerular basement membrane (GBM), the Goodpasture antigen which is recognized by the pathogenically important human antibodies shown to mediate nephritis in transfer experiments. Moreover the levels of anti-BPI in the IgG fraction could be augmented by preincubation with glycine pH 2.5 for 30 min. This anti-BPI activity could be inhibited by addition of the unbound material from the protein G column and this inhibitory material was not heat-labile at 56 degrees C. The molecular specificity of this autoreactivity was confirmed using recombinant BPI in coincubation experiments and the epitope localized to the C or N terminal moieties by the use of recombinant fusion proteins.

Anti-neutrophil cytoplasmic autoantibodies (ANCA) to bactericidal/permeability-increasing (BPI) protein recognize the carboxyl terminal domain

OBJECTIVES

to identify the region of bactericidal/permeability-increasing protein (BPI) recognized by anti-BPI ANCA.

METHODS

sera from 140 patients with a variety of clinical diagnoses (20 systemic vasculitis, 12 cystic fibrosis, 22 bronchiectasis/chronic obstructive airways disease, three diabetes mellitus, 13 chronic renal failure, 12 primary sclerosing cholangitis, eight ulcerative colitis, three Crohn's disease, seven cancer, and 40 other or unknown diagnoses) known to be reactive against native (nBPI), were screened by solid phase enzyme linked immunosorbent assay (ELISA) against a panel of recombinant fusion proteins; holo BPI (rBPI), recombinant lipopolysaccharide binding protein (rLBP), an N-terminal fragment of rBPI (rBPI21 ) and 'fusion' proteins containing the C- or N-terminal ends of BPI spliced with N-or C-ends of LBP, respectively.

RESULTS

a strong correlation was seen between the degree of reactivity to rBPI and the BPI C-terminal fusion protein, r=0.69, P < 0.001, as well as between nBPI and rBPI protein, r=0.55, P < 0.001, but not between nBPI and the N-terminal region of BPI (rBPI21), or proteins containing only the N-terminal fragment. Binding to proteins containing the BPI C-terminus was confirmed to be specific by fluid phase inhibition ELISA and Western blot analyses.

CONCLUSIONS

together these data suggest that circulating autoantibodies to BPI from patients with different diseases recognize the C-terminal region of BPI.

The inhibition of myeloperoxidase by ceruloplasmin can be reversed by anti-myeloperoxidase antibodies

BACKGROUND

The purpose of this study was to characterize the recently reported inhibition of myeloperoxidase (MPO) by ceruloplasmin and to determine whether this may be disturbed in the presence of anti-MPO antibodies.

METHODS

Specificity of the binding between ceruloplasmin and MPO was confirmed by Western blotting and enzyme-linked immunosorbent assay (ELISA), and the enzymatic activity of MPO was measured in the presence of ceruloplasmin, affinity-purified anti-MPO antibodies, or both. The affinity of the binding between MPO and ceruloplasmin and MPO and the anti-MPO antibodies was measured using a biosensor, with the results confirmed by chaotrope ELISA.

RESULTS

Affinity-purified anti-MPO antibodies from patients with microscopic polyangiitis and florid renal vasculitis inhibited the binding between ceruloplasmin and MPO to a maximum of 72.9 +/- 12.8%, whereas those from patients with Wegener's granulomatosis and only minimal renal involvement inhibited the binding to a maximum of only 36.8 +/- 10.9% (P < 0. 001), with comparable reversal of the ceruloplasmin-mediated inhibition of MPO activity. Measurement of the affinity of the interactions demonstrated that binding between MPO and the anti-MPO antibodies is stronger than that between MPO and ceruloplasmin (1.61 x 107 to 1.33 x 108 vs. 7.46 x 106 m-1), indicating that binding to the autoantibody would be favored in vivo.

CONCLUSIONS

This study confirms a role for ceruloplasmin as a physiological inhibitor of MPO, and demonstrates how the inhibition may be disrupted in the presence of anti-MPO antibodies. Because a majority (16 of 21) of the antibodies did not themselves inhibit MPO activity, their interference with the inhibition mediated by ceruloplasmin may be brought about by steric hindrance consequent upon the binding of the antibody to a dominant epitope at or near the active site.

Semi-specific immuno-absorption and monoclonal antibody therapy in ANCA positive vasculitis: experience in four cases

The treatment of renal limited systemic vasculitis usually involves a combination of cytotoxic drugs and steroids. As shown by randomised prospective controlled trial, plasmapheresis may be of additional benefit for the management of patients with renal involvement severe enough to require dialysis support. Recently, growing evidence has suggested that autoantibodies to neutrophil cytoplasm (ANCA) may play a role in the pathogenesis of the primary vasculitides by promoting neutrophil mediated endothelial cell cytotoxicity. This has led to new strategies for treatment based on firstly, the use of semi-specific immunoabsorption (IA) devices to remove circulating autoantibodies, and secondly, the use of 'Humanised' monoclonal antibodies (MAbs) with specificity for lymphocytes, particularly T lymphocytes. We have treated four patients, two with ANCA specificity for proteinase 3 (PR3), and two with specificity for myeloperoxidase (MPO). Semi-specific IA was carried out by plasmapheresis through extracorporeal online devices, using L tryptophan as the immobilised immunoabsorbant. Of the four patients who received IA, three showed substantial depletion in ANCA titres and resolution of clinical symptoms. The MAbs were subsequently used to attempt to obtain long-term control of ANCA synthesis. These results suggest that an optimal strategy for treatment of systemic vasculitis might consist of specific IA, using immobilised ANCA antigens to deplete circulating vasculotoxic antibodies, combined with MAb therapy to restore immune homeostasis.

Tracheal involvement in Wegener's granulomatosis: evaluation using spiral CT

OBJECTIVE

To describe the computed tomography (CT) appearances of tracheal stenosis in Wegener's granulomatosis (WG) and to assess the additional value of reformatted images.

PATIENTS AND METHODS

Ten patients with tracheal involvement by WG were assessed with spiral CT and both coronal and three-dimensional surface shaded images were generated. Fibreoptic bronchoscopy was also performed in all patients.

RESULTS

Ninety per cent of lesions were situated in the subglottic region. In all cases there was circumferential mucosal thickening, in nine cases extending over a relatively short distance (mean 2.4 cm). The degree of narrowing of the axial luminal diameter ranged from 23% to 100%. In three patients there was contiguous involvement of the vocal cords evident on CT, two further cases with mild vocal cord inflammation were identified bronchoscopically. Other CT findings included mucosal irregularity and ulceration (50%), and involvement of the tracheal cartilages (20%).

CONCLUSION

Wegener's granulomatosis may involve the trachea with resultant stenosis. Spiral CT is an easily performed, non-invasive technique which provides accurate assessment of tracheal lesions and is complementary to bronchoscopy. The main additional advantage of coronal reformatted images was our added confidence in defining the upper and lower limits of lesions and in the evaluation of vocal cord involvement.

Refractory Wegener's granulomatosis: a model for shorter immunotherapy of autoimmune diseases

BACKGROUND

Humanised monoclonal antibodies are immunomodulatory tools with high specificity and sustained therapeutic potential. We investigated the effectiveness of treatment with monoclonal antibodies to lymphocyte CD52 and CD4 in patients with Wegener's granulomatosis that had proved intractable despite conventional treatment. We also investigated whether repeated courses of monoclonal antibody treatment alone could be used to control relapses in patients in remission.

METHOD

We studied 17 consecutive patients with refractory Wegener's granulomatosis seen between June 1992 and June 1996. In all patients, treatment with prednisolone and cyclophosphamide or azathioprine for at least six months had been unsuccessful, and all were followed up for at least six months after monoclonal antibody treatment. Diagnosis was established on clinical, serological and histological criteria. Disease activity in the upper airways, lungs or kidneys at referral was documented by whole-body scintiscanning, computed tomography, or isotope measurement of the glomerular filtration rate, as well as by tissue biopsy, where appropriate. Monoclonal antibodies to CD52 followed by CD4 were given intravenously in courses lasting five days each.

RESULTS

Remission (programmed withdrawal of drug treatment with no return of refractory disease) was obtained in 16 patients after one course of CD52 +/- CD4, and confirmed by serial studies of abnormalities found before treatment. In one patient, disease remained unchecked. In responders, cytotoxic drugs were stopped during monoclonal antibody treatment and were not used again, while steroids were tapered off gradually. Disease relapses occurred in nine. Monoclonal antibodies alone controlled these during follow-up that totalled 30 patient years. Neither systemic opportunistic infection nor lymphoma development complicated this regimen.

CONCLUSION

Monoclonal antibody treatment may be better and safer for diseases, such as Wegener's granulomatosis, that require long-term cytotoxic and steroid treatment because it speeds remission and avoids the iatrogenic complications of cumulative drug toxicity.

Myeloperoxidase autoantibodies distinguish vasculitis mediated by anti-neutrophil cytoplasm antibodies from immune complex disease in MRL/Mp-lpr/lpr mice: a spontaneous model for human microscopic angiitis

Anti-neutrophil cytoplasm antibodies (ANCA) with specificity for myeloperoxidase (MPO) occur in the sera of patients with microscopic angiitis, an autoimmune disease characterized by necrotizing vasculitis and crescentic glomerulonephritis. These autoantibodies have been shown to stimulate neutrophil degranulation and are believed to participate in pathogenesis. A neutrophilic vasculitis has been reported in MRL-lpr mice which has histological appearances similar to microscopic angiitis. In the present study we show that 22% of female MRL-lpr mice develop MPO autoantibodies. These animals develop a clinical syndrome of vasculitis and glomerulonephritis that is distinct from immune complex disease. Anti-MPO monoclonal antibodies derived from these mice are polyreactive and react with double-stranded DNA. They bind a conformational epitope on human MPO which is also expressed by activated human neutrophils. The results suggest that a subset of MRL-lpr mice develop ANCA-related vasculitis rather than systemic lupus erythematosus and may be used as a model for human microscopic angiitis.

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.

Antineutrophil cytoplasmic autoantibodies (ANCA) in children with cystic fibrosis

Anti-neutrophil cytoplasmic antibodies (ANCA) represent a useful diagnostic tool in patients with small vessel vasculitis. Circulating ANCA specific for bactericidal/permeability increasing protein (BPI) have been recently reported in adult patients with cystic fibrosis (CF), an autosomal recessive disorder caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene with consequent impaired function of a transmembrane chloride channel. To contribute to the better understanding of the significance of ANCA in this disease, we investigated ANCA presence and antigenic specificity in children with CF. Results were correlated with clinical status, immunological data, age and genotype. The indirect immunofluorescence pattern of a total of 71 children with CF indicated that 31 were c-ANCA positive, while seven were p-ANCA positive. In further ELISA studies of ANCA antigenic specificity, 51 out of 66 investigated samples were positive for BPI, and 14 out of 28 were positive for proteinase 3 (PR3). We found an association between levels of antibodies against PR3 with age and Pseudomonas infection. We did not, however, find any correlation between CFTR genotypes, Pseudomonas infection or paediatric parameters and the level of anti-BPI antibodies. High positivity of anti-BPI antibodies were seen even among the youngest CF patients, before the development of clinical signs of CF, indicating that formation of ANCA might be a very early event in the disease. Both anti-BPI and anti-PR3 antibodies may play a significant, although variable role, in the pathogenesis of CF.

Studies of epitope restriction on myeloperoxidase (MPO), an important antigen in systemic vasculitis

Anti-neutrophil cytoplasmic antibodies are important components of the inflammatory response in patients with systemic vasculitis. Their role in the pathogenesis of these conditions remains incompletely defined. Several antigens have been identified, and MPO is one of the most important. To gain more understanding of the immune mechanisms involved, we were keen to see if the antibody response to MPO was restricted, or whether there was a general loss of tolerance to the whole surface of the molecule. To study the epitopes we employed both ELISA and biosensor technology, and were able to demonstrate restriction both in the number and localization of the epitopes being recognized.

Use of native and recombinant bactericidal/permeability-increasing proteins (BPI) as antigens for detection of BPI-ANCA

Anti-neutrophil cytoplasmic antibodies (ANCA) against native bactericidal/permeability-increasing protein (nBPI) have gained increasing diagnostic significance in inflammatory bowel disease and cystic fibrosis. However, routine detection of BPI-ANCA requires pure antigen in large quantities. As nBPI is difficult to isolate and is very susceptible to proteolytic cleavage with subsequent epitope loss, it was the aim of this study to determine whether recombinant BPI (rBPI) can be used as an alternative to nBPI as target antigen for ANCA in diagnostic procedures. Therefore, 93 BPI-ELISA-positive sera and controls were compared in different ELISAs using nBPI, rBPI, unglycosylated rBPI and a 21-kDa amino-terminal fragment of rBPI. ELISA results were confirmed by immunoblotting and all sera were tested in indirect immunofluorescence (IFT). There was an 88% (82/93) agreement in recognition of nBPI and rBPI by ANCA in both ELISA systems, yet the quantitation of BPI-ANCA in relative units showed a less optimal result and correlated only by 45% (p < 0.01). Most sera recognized nBPI, rBPI and unglycosylated rBPI equally suggesting that glycosylation has no influence on antigen recognition. Only two sera were positive for the 21-kDa nBPI indicating that the binding sites for ANCA are either conformational epitopes and/or are located mainly on the carboxy-terminal part of the BPI molecule. Most BPI-ELISA-positive sera were negative in IFT (43%), but a perinuclear (pANCA, 30%), a cytoplasmic (cANCA,10%) or an atypical ANCA (aANCA, 2%) staining pattern, as well as a cytoplasmic pattern only on formaldehyde-fixed granulocytes (13%) were also observed. Overall, no characteristic pattern was seen for BPI-ELISA-positive sera in IFT. Taken together, these data suggest that rBPI offers an excellent alternative to nBPI for broad-based BPI-ANCA ELISA and will be of great value in further investigations of BPI-ANCA interactions.

Human autoimmune anti-proteinase 3 scFv from a phage display library

This is the first study describing recombinant human antibody fragments directed to the autoantigen proteinase 3 (PR3) from an immune B cell source. Detection of these autoantibodies has proven valid for the diagnosis and monitoring of Wegener's granulomatosis. The described antibody fragment (scFv) was isolated from a phage display library prepared from the IgG-positive splenic lymphocytes of a patient with systemic autoimmunity. The cloning strategy was designed to maintain the diversity of the antibody variable gene repertoire, and sequencing of several variable genes demonstrated that all major heavy and light chain families were represented. We found an over-representation of particular heavy chain variable domains in splenic lymphocytes which differ from the ones frequently found in peripheral blood lymphocytes. It was possible to obtain specific scFv to PR3 after a single round of selection and the binding could be inhibited by the patients' sera. Although the antibody fragments in the splenic repertoire were found to be highly mutated, it was interesting to find that the selected scFv showed only limited somatic mutation. Furthermore, we could demonstrate that the removal of the mutations had no effect on binding specificity.

Cerebral vasculitis--recognition, diagnosis and management

Cerebral vasculitis is a serious but uncommon condition which presents considerable difficulties in recognition, diagnosis and treatment. We studied eight consecutive patients in whom this diagnosis was made. Despite the great diversity of symptoms and signs, we noted three clinical patterns: (i) acute or sub-acute encephalopathy, (ii) a picture with some similarities to multiple sclerosis ('MS-plus'), and (iii) features of a rapidly progressive space-occupying lesion. The identification of these patterns may help recognition of cerebral vasculitis. The diagnostic value of four investigative procedures not previously studied in cerebral vasculitis was assessed: ophthalmological examination using low-dose fluorescein angiography with slit-lamp video microscopy of the anterior segment (abnormal in 4/5 patients); spinal fluid oligoclonal band analysis (abnormal in 3/6 patients); anti-neutrophil cytoplasmic antibody assay (abnormal in 3/8 patients); and indium-labelled white-cell cerebral imaging (positive in only one patient). Treatment was with steroid alone (n = 2) or steroid with cyclophosphamide (n = 6). Seven patients responded clinically.

Antineutrophil cytoplasm autoantibodies against bactericidal/permeability-increasing protein in inflammatory bowel disease

BACKGROUND

Bactericidal/permeability-increasing protein (BPI), a constituent of primary neutrophil granules, is a potent natural antibiotic and an antineutrophil cytoplasm antibody (ANCA) antigen in cases of vasculitis in which the target antigen is neither myeloperoxidase (MPO) nor proteinase-3 (PR3).

AIM

To investigate BPI as a possible target antigen for ANCAs in inflammatory bowel disease.

METHODS

ANCAs were detected by routine immunofluorescence (IIF) and solid phase enzyme linked immunosorbent assay (ELISA) performed for antibodies to the purified neutrophil granule proteins; MPO, PR3, cathepsin-G, lactoferrin, and BPI in serum samples from 88 patients with inflammatory bowel disease (36 with Crohn's disease, 52 with ulcerative colitis). Thirty patients with bacterial enteritis acted as controls.

RESULTS

Significantly more patients with ulcerative colitis were ANCA positive by IIF (60%) than patients with Crohn's disease (28%) or infectious enteritis (23%) (p < 0.001). IgG anti-BPI antibodies were present in 29% of patients with ulcerative colitis, 14% of patients with Crohn's disease, and 23% of patients with infectious enteritis, occurring in 44% of those patients with inflammatory bowel disease who were ANCA positive by IIF. Antibodies to other ANCA antigens were rare. The presence of ANCAs was not related to either disease activity or extent; presence of anti-BPI antibodies was significantly related to both a lower serum albumin concentration (p = 0.001) and a higher erythrocyte sedimentation rate (p = 0.02) in patients with ulcerative colitis, and to colonic involvement in patients with Crohn's disease (p = 0.01).

CONCLUSION

BPI is a significant minority target antigen for ANCAs in inflammatory bowel disease that seems related to colonic Crohn's disease and disease activity in ulcerative colitis. Anti-BPI antibodies occur in infectious enteritis.

Anti-native and recombinant myeloperoxidase monoclonals and human autoantibodies

Myeloperoxidase (MPO) is one of the main antigen targets of anti-neutrophil cytoplasmic antibodies (ANCA) in systemic vasculitides. It has been suggested that anti-MPO antibodies may recognize a single epitope on recombinant MPO. If confirmed on native MPO, this might allow specific therapeutic intervention with anti-idiotypic MoAbs to prevent antibody antigen interaction which is thought to cause activation of neutrophils and vasculitis. We searched for restriction in the epitope recognition profile in 50 patients with anti-MPO autoantibodies, using both native and recombinant MPO. Mouse monoclonals were purified and tested in competition assays. At least four epitopes were identified on native MPO using these monoclonals and only two were conserved on recombinant MPO. We found that human MPO autoantibody response was not restricted to a single epitope on native MPO, as all sera tested did not show the same profile in competitive studies with monoclonals. Furthermore, 30% of human anti-native MPO sera failed to recognize rMPO.

Treatment of refractory Wegener's granulomatosis with humanized monoclonal antibodies

Conventional immunosuppression for systemic vasculitides is limited by substantial side-effects, cumulative drug toxicity and refractoriness in some patients. Six Wegener's granulomatosis patients who had been refractory to conventional therapy for at least 6 months, were treated with humanized monoclonal antibodies specific to lymphocyte CD52 or CD4 antigens. Diagnosis was on clinicopathological grounds, supported by the presence of autoantibodies to Proteinase 3. Histological evidence of persistent disease activity was obtained for each patient. Humanized monoclonal anti-CD52, with or without anti-CD4, was given intravenously up to 40 mg/day for up to 10 days. Remission, (programmed withdrawal of drug therapy without return of refractory disease) was achieved in all patients. Cytotoxic drugs were discontinued at the time of monoclonal antibody treatment and not used again; steroids were withdrawn gradually. Four patients relapsed at 1.5, 5, 10 and 18 months, and were treated successfully with further monoclonal antibody therapy alone. Three years after the study began, five patients are well; one patient died at surgery whilst in remission. Humanized monoclonal antilymphocyte antibodies may provide an effective treatment in patients with systemic vasculitis which is refractory to steroids or cytotoxic agents, or who are intolerant of these drugs.

Intravenous immunoglobulin as sole therapy for systemic vasculitis

High-dose, pooled, i.v. immunoglobulin (IVIg) is a potential, alternative treatment for Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) which has shown promise in the treatment of refractory disease when administered with continuing immunosuppression. This study of six new patients with antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis and early disease, without threatened vital organ function, examined the therapeutic response to treatment with IVIg alone. IVIg was well tolerated and all six patients had early reductions in disease activity. Four entered full, clinical remission which lasted for at least 1 yr, while in two the responses were partial and transient, and they subsequently required conventional treatment. After 16-48 months of follow-up, two of the four patients in full remission relapsed, but the other two have remained well.

A comprehensive method to purify three major ANCA antigens: proteinase 3, myeloperoxidase and bactericidal/permeability-increasing protein from human neutrophil granule acid extract

Indirect immunofluorescence (IIF) techniques have shown that anti-neutrophil cytoplasm autoantibodies (ANCA) are useful serological markers for certain small vessel vasculitides and the non-vasculitic inflammatory disorders. ELISA procedures, using purified molecules as solid phase ligands, helped to identify proteinase 3 (PR3) and myeloperoxidase (MPO) as two major ANCA antigens; and recently we characterised bactericidal/permeability-increasing protein (BPI) as another important ANCA antigen. ANCA against these three antigens are associated with different clinical disorders. Therefore purified antigens are needed to determine these different autoantibody specificities in order to help diagnosis and guide treatment. Here we describe a method using Orange-A dye ligand chromatography and cation exchange chromatography for the sequential purification of PR3, MPO and BPI, from the same starting material, an acid extract of normal human neutrophil granules. After separation the three antigens were free of contamination by each other and no traces were found of other known minor ANCA antigens.

Development and standardization of solid phase assays for the detection of anti-neutrophil cytoplasmic antibodies (ANCA). A report on the second phase of an international cooperative study on the standardization of ANCA assays

Anti-neutrophil cytoplasmic antibodies (ANCA) are diagnostic markers for systemic vasculitis. They are classically detected by an indirect immunofluorescence test using normal donor neutrophils as substrate. This assay lacks antigenic specificity and is not quantitative. The 'EC/BCR Project for ANCA Assay Standardization' is an international collaboration study with the aim to develop and standardize solid phase assays for ANCA detection. In this part of the study the isolation and characterization of proteinase-3 and myeloperoxidase, the two main target molecules for ANCA, and the development and standardization of ELISAs with these antigens are described. Six laboratories successfully isolated purified proteinase-3 preparations that could be used. Three of these preparations, together with one myeloperoxidase preparation, were subsequently used for ANCA testing by ELISA. The ELISA technique was standardized in two rounds of testing in the 14 participating laboratories. The coefficient of variation of these new assays decreased from values of approx. 50% in the first round to approx. 20% in the second round. We conclude that purified proteinase-3 and myeloperoxidase can be used in standardized ELISAs for ANCA detection. Whether such procedures offer advantages over the IIF test will be determined in a prospective clinical study.

New treatment strategies for systemic vasculitis: the role of intravenous immune globulin therapy

Intravenous immune globulin (IVIG) is now under evaluation for the treatment of patients with the forms of systemic vasculitis associated with anti-neutrophil cytoplasmic antibodies (ANCA). Although IVIG may produce effects by a variety of mechanisms, including control of T-cell function, interference with cytokine action, and Fc receptor blockade, it is the regulation of autoantibody production by B cells, through idiotypic-anti-idiotypic reactions, that makes this treatment attractive for patients with systemic vasculitis. The author and others have shown the importance of ANCA idiotypic-anti-idiotypic reactions in vitro and demonstrated that these could be influenced by anti-idiotypic determinants present in IVIG. Thus F(ab')2 fragments of IVIG could block ANCA binding to antigen, in a dose-dependent fashion. The degree of inhibition was variable, ranging up to 100% for the ANCA-containing sera of certain patients. Similar inhibitory activity could be found in the sera of patients in remission after treatment, as well as in occasional patients whose disease remitted spontaneously, without drugs being used. Thus, IVIG appears to be particularly valuable in the management of vasculitis in the elderly, the very young and for pregnant women, as well as for those at any age who are vulnerable to infection.

Autoantibodies against bactericidal/permeability-increasing protein in patients with cystic fibrosis

Cystic fibrosis (CF), a genetic disorder, is characterized by chronic pulmonary infection/inflammation which leads to respiratory failure. The presence of anti-neutrophil cytoplasmic autoantibodies (ANCA) has previously been observed in the sera of patients with CF. In view of the known relationship of ANCA with primary vasculitis and of their putative pathogenetic role in these disorders, we studied the presence, specificity and isotype of ANCA and their clinical associations in 66 adult CF patients. None of the 66 CF samples had autoantibodies to the major ANCA antigens, proteinase 3 or myeloperoxidase. However, 60/66 (91%) CF samples contained IgG, and 55/66 (83%) IgA, autoantibodies to bactericidal/permeability-increasing protein (BPI), a recently-characterized ANCA specificity. All the IgA anti-BPI-positive samples were also IgG anti-BPI-positive. The autoantibody specificity was confirmed by inhibition assay and immunoblotting of CF sera against a neutrophil granule preparation. Furthermore, in this cross-sectional study, anti-BPI levels were inversely correlated with the observed reductions in FEV1 and FVC (IgA anti-BPI & FEV1: r = -0.508, p < 0.0001), and both IgG and IgA anti-BPI levels were higher in CF patients with secondary vasculitis (n = 6) than in those without (p < 0.05). ANCA with specificity for BPI were present in the majority of CF sera in this study and autoimmune processes may be associated with the development of pulmonary injury in CF.

Azurocidin is a novel antigen for anti-neutrophil cytoplasmic autoantibodies (ANCA) in systemic vasculitis

We isolated a 27-kD protein using cation exchange chromatography from an acid extract of neutrophil granules. N-terminal amino acid sequence analysis of the first 10 residues showed that this protein is azurocidin, a member of the family of neutral serine proteinase found in the neutrophil, which shares amino acid sequence homology with the three other neutral serine proteinases, elastase, proteinase 3 (PR3) and cathepsin G, but unlike them is without proteolytic activity. To test whether, in addition to these proteases, azurocidin might be a target for the humoral autoimmune responses associated with human vasculitis, 185 indirect immunofluorescence (IIF)-positive ANCA sera, made up of four groups of sera with specificities for PR3 (n=37), myeloperoxidase (MPO; n=50), bactericidal/permeability-increasing protein (BPI; n=41) and sera that recognized none of them (triple negative, n=57), and 46 normal sera were screened for IgG anti-azurocidin antibodies using an ELISA incorporating purified azurocidin. Twenty of the 185 IIF-positive sera and 2/46 normal sera displayed reactivity with azurocidin. Positive sera could blot the 27-kD band by Western blot analysis. Further study of the 20 positive sera revealed that: (i) 10 also had autoreactivity for MPO, of which six additionally recognized lactoferrin; (ii) two had reactivity with BPI; (iii) the remaining eight sera were positive only for azurocidin. All 20 sera were from patients with systemic vasculitis, and four of the six sera with triple reactivity (for azurocidin, MPO and lactoferrin) were from patients with hydralazine-induced vasculitis. We concluded that: (i) azurocidin is a novel ANCA antigen; (ii) anti-azurocidin antibodies from a subgroup of patients might represent the consequence of a drug-induced multi-clone activation.

Antigen specificity in hydralazine associated ANCA positive systemic vasculitis

The anti-hypertensive agent hydralazine can cause a lupus-like syndrome characterized by serosal inflammation, arthralgias and rashes. The kidneys however are usually spared. The condition is characterized by circulating immune complexes and antinuclear antibodies, whilst antibodies against double-stranded DNA are rare. Hydralazine can also cause a systemic vasculitis with a pauci-immune rapidly progressive glomerulonephritis, which is associated with autoantibodies directed against components of the neutrophil cytoplasm. In this study, ten patients with hydralazine-induced vasculitis had antibodies with specificities for both myeloperoxidase and lactoferrin. We suggest that this particular pattern of autoantibodies, together with antibodies with reactivity against nuclear components including double-stranded DNA, are characteristic findings in hydralazine-induced vasculitis. In addition, renal involvement appears to be more common in this group of patients with vasculitis than in those with the lupus-like syndrome.

Neutrophil and recombinant myeloperoxidase as antigens in ANCA positive systemic vasculitis

Myeloperoxidase (MPO) is one of the major autoantigens recognized by anti-neutrophil cytoplasm antibodies. The association of this antigen with specific disease entities requires that there is a source of pure antigen present in large quantities. Further delineation of the molecular mechanisms involved in the antigen-antibody interaction requires the ability to manipulate the molecule. The expression of recombinant MPO in Chinese hamster ovary cells has produced a source of pure protein, suitable for molecular studies. We have shown that this protein is an antigen recognized by 95% of anti-MPO antibodies from patients with systemic vasculitis. This recombinant molecule will be of use in providing an additional specific solid-phase assay for these antibodies and further forms of this protein which mirror the antigenicity of native MPO more exactly may replace chemically purified antigen. It will also be of great value in studies examining the epitopes recognized by anti-MPO antibodies and in studies of immunoregulation and T cell activation.

Anti-neutrophil cytoplasm antibodies and anti-glomerular basement membrane antibodies: two coexisting distinct autoreactivities detectable in patients with rapidly progressive glomerulonephritis

Circulating autoantibodies against the Goodpasture antigen (alpha 3 chain of type IV collagen) in the glomerular basement membrane (anti-GBM) and anti-neutrophil cytoplasm antibodies (ANCA) are each associated clinically with the development of a rapidly progressive glomerulonephritis. Antibodies with both these specificities coexist in a subset of patients, raising the possibility that they might be a result of cross-reactivity. In this study we have shown that 21% of patients with anti-GBM antibodies also had ANCA, and by using cross-inhibition assays, antigen-specific enzyme-linked immunosorbent assays, and Western blot analysis, these were shown to be two distinct populations of autoantibodies. In patients with both specificities, a greater proportion of the ANCA had specificity for myeloperoxidase (73.5%) than in patients with ANCA alone (36.6%). The presence of ANCA should be ascertained in all patients with anti-GBM disease as the prognosis for these double-positive patients may be dependent on both populations of antibodies.

Peripheral blood T lymphocytes in systemic vasculitis: increased T cell receptor V beta 2 gene usage in microscopic polyarteritis

Antigen recognition by T lymphocytes is mediated by cell surface receptors T cell specificity depends on the variable, diversity and junctional (VDJ) regions of the alpha and beta polypeptide chains of the T cell receptor (TCR). The expression of the variable region genes of the beta chain (V beta) has been analysed to study the involvement of peripheral blood T cells in systemic vasculitis. RNA was extracted from peripheral blood lymphocytes of 12 patients with microscopic polyarteritis, 10 with Wegener's granulomatosis, six with unclassified vasculitis, and 28 healthy age- and sex-matched individuals. Complementary DNA was made from RNA and amplified by the anchored polymerase chain reaction (PCR) using redundant oligonucleotide primers for the TCR V beta genes. To determine if the dominant usage of a V beta gene family reflected the presence of particular T cell clones, cDNA was amplified with primers for the specific V beta gene family. The product was screened for sequence homogeneity by single-stranded conformational polymorphism (SSCP) and cloned to sequence the adjoining TCR (D beta) J beta region. A significant increase in the mean percentage expression of the V beta 2.1 gene was seen in vasculitis patients (11.4 + 1.0% (mean + s.e.m.)) compared with controls (6.6 + 0.6%; P < 0.003). The most marked increase was seen in microscopic polyarteritis (13.9 + 1.7%; P < 0.0001). There were also increases in the expression of V beta 3, 13 and 14 in peripheral blood of vasculitis patients compared with controls. SSCP analysis of V beta 2.1 amplified products indicated the presence of oligoclonal bands in a smaller proportion of patients (8/27) than controls (12/28). There was no strong evidence for the conservation of the TCR V beta 2.1 junctional region sequence data from a sample group of three patients with oligoclonal bands. Thus, a subset of patients with systemic vasculitis, particularly those with microscopic polyarteritis, have increased TCR V beta 2.1 gene expression in their peripheral blood T cell repertoire. As superantigens binding V beta 2.1 are postulated to activate T cells with diverse CDR3 sequences, it is proposed that a superantigen is involved in the immunopathogenesis of vasculitis.

Management of systemic vasculitis: contribution of scintigraphic imaging to evaluation of disease activity and classification

The use of radio-isotope-labelled leucocyte scans has become established as a non-invasive and accurate means of diagnosing a variety of inflammatory conditions. We report a retrospective study on leucocyte imaging in the management of 50 patients with systemic vasculitis. Leucocyte imaging was useful for detecting unsuspected sites of disease and monitoring disease activity. Scintigraphy was superior to conventional radiography or CT scanning for detecting and monitoring vasculitic involvement of the respiratory tract. The scans were useful for differentiating between Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA). There was a close and statistically significant relationship between the clinical diagnosis of WG and nasal uptake on leucocyte scans (p < 0.01), whereas in patients with MPA it was rare. Anti-proteinase 3 autoantibody specificity correlated significantly with nasal uptake of labelled leucocytes (p < 0.03). Leucocyte imaging is a useful non-invasive investigation in patients with systemic vasculitis.

The immunosuppressive drug thalidomide induces T helper cell type 2 (Th2) and concomitantly inhibits Th1 cytokine production in mitogen- and antigen-stimulated human peripheral blood mononuclear cell cultures

Thalidomide is an effective immunomodulatory drug in man, but its mechanism of action remains unclear. We hypothesized that, in addition to its reported inhibitory effects on production of monocyte-derived tumour necrosis factor-alpha (TNF-alpha), thalidomide might be effective at the level of Th immunoregulation. In a comparative study with the immunosuppressant cyclosporin A, we have demonstrated a potent and specific effect of thalidomide on cytokine production relating to the distinct Th1 and Th2 subsets. It induced and enhanced the production of IL-4 and IL-5 and, at the same dose (1000 ng/ml), significantly inhibited interferon-gamma (IFN-gamma) production in phytohaemagglutinin (PHA)-stimulated human peripheral blood mononuclear cell (PBMC) cultures. Stimulation of PBMC with recall antigen (streptokinase:streptodornase (SKSD)) at 144 h in the absence of thalidomide resulted in a predominantly Th1 response, with the production of IFN-gamma and IL-2. Thalidomide switched this response from a Th1 to a Th2 type. The effect was most pronounced at 1000 ng/ml thalidomide, where inhibition of IFN-gamma and enhancement of IL-4 production was maximal. In unstimulated cultures thalidomide alone induced IL-4 production. Cyclosporin A, in contrast, inhibited both Th1 and Th2 cytokine production by PHA-stimulated PBMC. Time course data from thalidomide-treated cultures revealed that the augmented IL-4 production diminished as the culture time increased, whereas IFN-gamma production was significantly increased. This response might be due to activation-induced apoptosis of Th2 cells or the induction of Th2 cell anergy, in the continued presence of stimulating agents, with the emergence of IFN-gamma-secreting Th1 cells when Th2 antagonism declines. The effects of thalidomide and related compounds may enhance our understanding of the mechanisms of T helper cell selection, offer the possibility of controlled therapeutic switching between Th1 and Th2 responses, and may lead to a rational approach for the treatment of some T cell-mediated immunological disorders.

Antineutrophil cytoplasmic antibodies and their relevance to the dermatologist

The term vasculitis embraces a heterogeneous group of conditions which may occur as primary phenomena or secondary to disorders such as rheumatoid arthritis or systemic lupus erythematosus. Classification of vasculitis is often difficult in the absence of identifiable aetiological factors or specific serological markers. However, the primary systemic vasculitides can be segregated morphologically, according to the size of blood vessels involved and the presence of granulomata (Table 1). Recently, the discovery of circulating antineutrophil cytoplasmic antibodies (ANCA) in many patients with these disorders, whose differing specificities substantiate the histological classification, has led to interest being focused on their relevance in the development of vasculitis. This paper reviews the historical aspects of the detection of ANCA, and the value of these antibodies in the diagnosis and management of the primary systemic vasculitides likely to be encountered by the dermatologist. The clinical features in patients with these vasculitides are also outlined.

ANCA and predicting relapse in systemic vasculitis

We studied 60 patients with ANCA-positive systemic vasculitis (SV) to assess the prognostic significance of clinical and serological features at presentation, and the value of sequential monitoring of ANCA, C-reactive protein (CRP) and ESR levels as predictors of disease relapse. Patients were recruited at the time of diagnosis, treated with a standard protocol, and assessed monthly for one year. Clinical remission was achieved in 56/60 (93%), and ANCA became undetectable in 50/60 (83%) after treatment. During the one year follow-up period, disease relapses were seen in 23 (38%) patients. No specific associations were observed between initial disease presentation, initial ANCA level or ANCA antigenic specificity and relapse. However, 13/23 (57%) of relapses were preceded by a rise in ANCA a mean of 7.8 weeks earlier, while at the time of relapse 19/23 (83%) were ANCA-positive. Rises in CRP and ESR occurred in 23/60 (38%) and 14/43 (33%), respectively, but were less closely associated with relapse than ANCA. A sustained rise in ANCA was seen in six patients without relapse while clinical relapse occurred with a negative ANCA in four. Sequential ANCA monitoring at monthly intervals during disease remission is of value, at least during the first year, in the prediction and diagnosis of relapse in SV, and is superior to measurement of CRP or ESR.