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Objectives: The aim of this study was to analyse the role of netting neutrophils in the pathogenesis of granulomatosis with polyangiitis (GPA), especially their interplay with peripheral blood mononuclear cells (PBMCs)., Methods: The amount of cell-free DNA (cfDNA) was determined in sera from GPA patients (pairs active/inactive state of disease, n=18) and from healthy controls (HCs, n=10). Furthermore, we performed in vitro incubation experiments using PBMCs and NETs from patients and HCs for accessing the effect of NETs on PBMC behaviour. We determined proliferation of T- and B-cells (CSFE assay), B-cell maturation (CD38 staining and flow cytometry), production of IgG (ELISpot, ELISA), and secretion of the cytokines IFN-γ, IL-4, IL-10, IL-17A (ELISA)., Results: We detected a significant increase in serum cfDNA levels of GPA patients compared to HCs. The concentration of cfDNA was associated with disease activity. NETs of patients and HCs induced proliferation of CD4+ T- cells and CD19+ B-cells and maturation of B-cells. Furthermore, we detected an increase in IL-17A secretion after stimulating PBMCs with NETs. A significant difference between PBMCs from GPA patients and HCs was not detectable., Conclusions: NETs activate PBMCs of HCs and GPA patients. Our findings give supportive evidence that NETosis plays a role in the pathogenesis of GPA.

Autoantibodies to nuclear antigens arise in human autoimmune diseases, but a unifying pathogenetic mechanism remains elusive. Recently we reported that exposure of neutrophils to inflammatory conditions induces the citrullination of core histones by peptidylarginine deiminase 4 (PAD4) and that patients with autoimmune disorders produce autoantibodies that recognize such citrullinated histones. Here we identify histone H1 as an additional substrate of PAD4, localize H1 within neutrophil extracellular traps, and detect autoantibodies to citrullinated H1 in 6% of sera from patients with systemic lupus erythematosus and Sjögren's syndrome. No preference for deiminated H1 was observed in healthy control sera and sera from patients with scleroderma or rheumatoid arthritis. We map binding to the winged helix of H1 and determine that citrulline 53 represents a key determinant of the autoantibody epitope. In addition, we quantitate RNA for H1 histone subtypes in mature human neutrophils and identify citrulline residues by liquid chromatography and tandem mass spectrometry. Our results indicate that deimination of linker histones generates new autoantibody epitopes with enhanced potential for stimulating autoreactive human B cells.-Dwivedi, N., Neeli, I., Schall, N., Wan, H., Desiderio, D. M., Csernok, E., Thompson, P. R., Dali, H., Briand, J.-P., Muller, S., Radic, M. Deimination of linker histones links neutrophil extracellular trap release with autoantibodies in systemic autoimmunity., (© FASEB.)

Objective: The aim of the study was to characterize the expression of TLR2, TLR4 and TLR9 in PMNs of patients with granulomatosis with polyangiitis (GPA) and to elucidate the role of these receptors in GPA with respect to neutrophil activation., Methods: The expression of TLR2, TLR4 and TLR9 was determined on ex vivo PMNs in whole blood samples of GPA patients (n = 35) and healthy controls (HCs) (n = 24). Isolated PMNs were stimulated in vitro with TLR agonists and assessed for degranulation, membrane proteinase 3 (mPR3) expression, soluble l-selectin shedding and cytokine production (IL-8) in five GPA patients and five HCs. The priming effects of TLR2 and TLR9 ligation were assessed by measurement of serine protease activity after stimulation with PR3-ANCA., Results: There were no significant differences in the ex vivo expression of TLRs on PMNs in HCs and GPA patients. Stimulation of TLR4 and TLR9 induced MPO release, stimulation with TLR2, TLR4 and TLR9 ligands elicited IL-8 production and stimulation of TLR2 and TLR9 led to an upregulation in mPR3 expression on PMNs with no significant differences between GPA and HC after 1 or 24 h stimulation. Priming of PMNs with TLR2 and TLR9 ligands induced degranulation after subsequent stimulation with PR3-ANCA, which was comparable to priming with TNF-α., Conclusion: Expression of TLR2, TLR4 and TLR9 in PMNs and the TLR-induced activation of PMNs was comparable in GPA and HC. mPR3 upregulation by TLR2 and TLR9 stimulation and the priming effect of TLR ligands on PMNs may have a potential implication for triggering disease activity during infection in GPA.

In Wegener's granulomatosis (WG), a pathogenetic role has been proposed for circulating anti-neutrophil-cytoplasmic antibodies (ANCA) targeting proteinase 3 (PR3). Disease activation in WG appears to be triggered by bacterial infections. In the present study, we characterized the effect of anti-PR3 antibodies on in vitro activation of isolated monocytes and neutrophils by the bacterial cell-wall components lipopolysaccharide (LPS) and lipoteichoic acid (LTA). Although sole incubation of monocytes and neutrophils with monoclonal anti-PR3 antibodies induced the release of minor quantities of the chemokine interleukin-8 (IL-8), preincubation with anti-PR3 antibodies, but not with isotype-matched control immunogloblin G (IgG), resulted in a markedly enhanced IL-8 liberation upon LPS challenge. The priming response was evident after 2 h of preincubation with anti-PR3 and peaked after 6 h. The anti-PR3-related priming was also observed for tumor necrosis factor alpha (TNF-alpha) and IL-6 synthesis. Comparable priming occurred when leukocytes were preincubated with ANCA-IgG derived from WG serum but not with normal IgG. The priming effect of the anti-PR3 antibody pretreatment was reproduced for LTA challenge of monocytes and neutrophils but not for leukocyte stimulation with TNF-alpha. Flow cytometric analysis revealed an increase in monocyte and neutrophil membrane CD14 expression during the anti-PR3 priming. We conclude that cytoplasmic ANCA specifically prime CD14-dependent monocytes and neutrophils for activation. The resulting enhanced responsiveness to bacterial pathogens may contribute to the development and maintenance of inflammatory lesions during active WG.

Severe combined immunodeficient mice reconstituted with human leukocytes have been useful to model parts of the human immune system, including some of its diseases (e.g., AIDS). Because no human polymorphonuclear leukocytes (huPMN) develop in these xenograft models, diseases such as several forms of vasculitis cannot be modeled using this approach. To provide such a model for vasculitis, human skin patches were grafted onto double-knockout Pfp(-/-)Rag2(-/-) mice, which not only lack functional T and B cells but which are also devoid of natural killer cells. After intravenous injection, a high proportion of huPMNs survived within the circulation and accumulated in the human blood vessels. The accumulation increased considerably after the endothelium of the skin patches had been stimulated by tumor necrosis factor-alpha. Alpha mild perivascular neutrophilic infiltration and vascular necrosis was observed in the microvessels of the skin patches. Thus, a xenograft model of vasculitis with predominant huPMNs infiltration has been established for the first time.

Anti-neutrophil cytoplasmic antibodies (ANCA) targeting proteinase 3 (PR3) possess a high sensitivity and specificity for Wegener's granulomatosis. Due to their capacity of directly activating neutrophils, a pathogenetic role for these autoantibodies has been proposed. We investigated the impact of subthreshold concentrations of monoclonal anti-PR3 antibodies (anti-PR3; 0.1 microg/mL) on neutrophil activation elicited by a secondary agent. Preincubation with anti-PR3 resulted in a massive amplification of N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced leukotriene (LT) generation, with a marked increase in the liberation of LTB4, LTA4, and 5-hydroxyeicosatetraenoic acid (5-HETE). This priming commenced within 2.5 min, with a maximum after 5-7.5 min. Moreover, anti-PR3 pretreatment markedly enhanced PMN movement toward fMLP. The priming effect of anti-PR3 toward fMLP challenge was reproduced by c-ANCA, but not by F(ab)2 fragments of the antibodies and isotype-matched control IgG. Generation of superoxide anion and release of elastase were suppressed in anti-PR3-pretreated neutrophils undergoing fMLP challenge. In contrast, neutrophil activation by platelet-activating factor (PAF) or the calcium ionophore A23187 remained unaffected. We conclude that subthreshold concentrations of anti-PR3 antibodies selectively modify neutrophil responses to fMLP, with enhancement of leukotriene generation and chemotaxis, but suppression of respiratory burst and degranulation. Such priming might contribute to localized neutrophil accumulation together with blunted host defense in Wegener's granulomatosis.

Since proteinase 3 (PR3)-ANCA interact with PR3 on the surface of apoptotic polymorphonuclear neutrophils (PMN) and ingestion of apoptotic PMN is known to modulate macrophage inflammatory reactions, we raised the question whether PR3-ANCA-opsonized apoptotic PMN influence the uptake by macrophages and their state of activation. We therefore analysed the effects of PR3-ANCA-opsonized apoptotic PMN on the uptake process by enzymatic assay. We further investigated the production of TNF-alpha, IL-10, IL-12 and the secretion of lipid inflammatory mediators (TxB2, leukotriene B4 (LTB4) and prostaglandin E2 (PGE2)) by human monocyte-derived macrophages using FACS and ELISA methods. We show that PMN-opsonization by PR3-ANCA substantially enhances phagocytosis by macrophages and thereby triggers the production of TNF-alpha and TxB2. These in vitro findings indicate that PR3-ANCA opsonization of apoptotic PMN might be an important mechanism in the pathogenesis of Wegener's granulomatosis (WG), prompting macrophages to produce proinflammatory mediators. These mediators, mainly TNF-alpha, might prime further PMN leading to perpetuation of the known priming-dependent mechanisms of ANCA action.

The theoretical risk of triggering vasculitis resulting from administration of G-CSF and GM-CSF to patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV), such as Wegener's granulomatosis (WG), who develop agranulocytosis due to cytotoxic therapy, is unknown. Since there is strong evidence that activation of polymorphonuclear neutrophils (PMN) induced by binding of ANCA to PR3 or myeloperoxidase (MPO) expressed on their plasma membrane is involved in the pathogenesis of systemic vasculitides (SV), we studied the surface expression of PR3 and MPO on PMN from healthy donors in response to G-CSF and GM-CSF in vitro by flow cytometric analysis. Increasing doses of G-CSF did not alter PR3 expression on either untreated or tumour necrosis factor-alpha (TNF-alpha)-primed donor PMN significantly. In contrast, GM-CSF significantly increased PR3 membrane expression on both intact PMN and neutrophils primed with TNF-alpha. MPO expression was not significantly altered by either G-CSF or GM-CSF. In summary, these data demonstrate that GM-CSF, but not G-CSF, induces plasma membrane expression of PR3 on PMN in vitro. Since in AAV accessibility of the antigen (PR3 or MPO) to the antibody (ANCA) on the plasma membrane of PMN is thought to be essential for neutrophil activation by ANCA, the results of the present study suggest that administration of GM-CSF to patients with WG with neutropenia implies a definite theoretical risk of deterioration of vasculitis via this mechanism.

Human polymorphonuclear neutrophils (PMN) are regulated by soluble factors such as chemotactic peptides and cytokines. PMN themselves are capable of synthesizing and releasing various cytokines, thereby taking part in the afferent or inductive limb of the immune response. We report for the first time that TGFbeta2 can be synthesized and released by PMN obtained from peripheral blood. Reverse transcriptase polymerase chain reaction (RT-PCR) showed that preparations of PMN express mRNA for transforming growth factor (TGF)beta1 and TGFbeta2 but not for TGFbeta3. Only translation of TGFbeta2 into protein was observed applying different assays. Interestingly, TGFbeta2 in supernatants from stimulated PMN could be detected in the bioactive form.

Background: To obtain insight into the mechanisms of tissue injury in lung disease due to Churg-Strauss syndrome (CSS), the bronchoalveolar lavage (BAL) cell profile and the levels in the BAL fluid of cell products released by activated eosinophils and neutrophils were assessed., Methods: Thirteen patients with active progressive CSS (n = 7) or CSS in partial remission (n = 6) underwent clinical staging and bronchoalveolar lavage. The levels of eosinophil cationic protein (ECP), myeloperoxidase (MPO), and peroxidase activity in the BAL fluid were determined and the results were compared with those of 19 patients with pulmonary active Wegener's granulomatosis (WG) and nine control subjects., Results: In patients with progressive CSS the BAL cell profile was dominated by eosinophils, neutrophil elevation being the exception. The eosinophilia was associated with high ECP levels (4.39 ng/ml and 0. 40 ng/ml in the two CSS groups compared with unmeasurable values in the controls). Individual patients with highly active CSS also had raised MPO levels, comparable to the levels in the most active WG patients. Peroxidase activity in the BAL fluid was 1.26 U/ml and 0. 10 U/ml in the two groups of patients with CSS and 0.20 U/ml in the controls. Pulmonary disease in patients with WG was characterised by an extensive increase in MPO (0.30 ng/ml versus 0.13 ng/ml in the controls) together with high peroxidase activity in the BAL fluid (4. 37 U/ml), but only a small increase in ECP levels was seen. No correlation was found between the ECP and MPO levels in patients with CSS which suggests that eosinophil and neutrophil activation vary independently of each other., Conclusions: These findings suggest that, in addition to eosinophil activation, neutrophil activation is an important feature in some patients with highly active CSS. The balance of neutrophil and eosinophil involvement appears to be variable and this may be one explanation for the individually variable treatment requirements of patients with CSS.

TGF beta is a multifunctional cytokine modulating onset and course of autoimmune diseases as shown in experimental models. Aim of this study was to investigate possible interactions of TGF beta with lysosomal enzymes identified as ANCA autoantigens (e.g. proteinase 3, PR3). This included TGF beta effects on the translocation the lysosomal enzymes to the cell surface of polymorphonuclear cells (PMN), and the presumabe activation of non bioactive, latent TGF beta by these enzymes. Flow cytometry analysis showed TGF beta 1 to be a potent translocation factor for PR3 comparable with other neutrophil activating factors such as interleukin 8 (IL8). The PR3 membrane expression on primed PMN increased by up to 51% after incubation with TGF beta 1. PR3 itself was revealed as a potent activator of latent TGF beta, thus mediating bioeffects of this cytokine. Patients with various types of systemic vasculitis (SV) showed marked TGF beta overexpression correlating with disease. Mean TGF beta 1 plasma levels in the ANCA associated vasculitis (AAV) patients ranged from 8.9 (Wegeners granulomatosis, WG) to 13.3 ng/ml (Churg-Strauss syndrome, CSS)(control: 4.2 ng/ml, p < 0.01) while TGF beta 2 levels were not elevated. Our findings, together with other features of TGF beta's such as induction of angiogenesis and its strong chemotactic capacity, indicate that TGF beta might serve as a proinflammatory factor in SV, especially in AAV.

Objective: To determine the incidence of antineutrophil cytoplasmic antibodies (ANCA) in rheumatoid arthritis (RA), to detect the target antigens of ANCA, and to compare clinical and laboratory data of ANCA+ with ANCA- patients with RA., Methods: 385 sera of patients with RA were screened for ANCA by indirect immunofluorescence. ANCA+ sera were further analyzed for target antigens by ELISA: The ANCA+ patients were compared to randomly selected ANCA- patients with RA with respect to serological and radiological variables and extraarticular involvement., Results: ANCA were found in 16% of patients with RA (61/385 sera). All sera showed a perinuclear (pANCA) pattern. Antibodies directed against proteinase 3 were not observed. The analysis of ANCA+ and ANCA- patients revealed that the pANCA+ group exhibited significantly higher serological markers of inflammation (p < 0.005) and a higher incidence of rheumatoid factor (p < 0.005). Furthermore, vasculitic involvement was found at a higher frequency (p < 0.05) in the pANCA+ group. Five patients in the pANCA+ group had pulmonary involvement, but none in the pANCA- group., Conclusion: pANCA in RA may be a marker for a more aggressive course of disease in respect to serological variables and extraarticular manifestations including rheumatoid vasculitis and lung involvement.

Antineutrophil cytoplasmic antibodies (ANCA) encompass a heterogeneous group of autoantibodies targeting antigens in neutrophils (PMN), monocytes, and endothelial cells. ANCA are routinely detected by the indirect immunofluorescence technique (IFT) and at least three different patterns of fluorescence can be distinguished which have been assigned the acronyms cANCA, pANCA and aANCA. cANCA is mostly induced by proteinase 3 (PR3) antibodies (PR3-ANCA), and pANCA by myeloperoxidase (MPO) antibodies (MPO-ANCA), while aANCA has unidentified subspecificity. Over the past decade, ANCA have been the subject of extensive investigation. They have proved to be of significant value both as diagnostic tools and for follow-up in several forms of systemic vasculitis (e.g. Wegener's granulomatosis, WG; microscopic polyarteritis, MPA; Churg-Strauss syndrome, CSS) which are now termed 'ANCA-associated vasculitides'. Furthermore, it is suspected that the presence of ANCA is an important factor in the pathogenesis of these disease groups. Data regarding the detection of ANCA and their diagnostic value and role in the pathogenesis of vasculitic disorders will be discussed in this review. Growing evidence points to a pathophysiological and diagnostic relevance of the distribution of the ANCA target antigens PR3 and MPO (presence in the circulation, on cell membranes, and in tissue extracellularly). An autoimmune process has been implicated in the pathogenesis of ANCA-associated vasculitis, but it is uncertain which mechanism underlies the induction of the ANCA-related immunoresponse. In this paper mechanisms such as antigenic cross-reactivity between human PMN proteins and extrinsic antigens by molecular mimicry, idiotypic immunoglobulin regulation, and T-cell reactivity to PR3 and MPO will be discussed.

The presence of anti-neutrophil cytoplasmic Abs (ANCA) in many patients with systemic vasculitis suggests that ANCA may play a role in disease pathogenesis. Neutrophils from patients with Wegener's granulomatosis often express ANCA target Ags (myeloperoxidase (MPO) and proteinase 3 (PR3)) on their surface, making these intracellular primary granule enzymes accessible to these autoantibodies. Similarly, normal neutrophils can be induced to translocate MPO and PR3 to the cell surface in vitro, and we demonstrate that murine mAb ANCA IgG, but not IgM, binds to the ANCA target and engages the Fc gamma RIIa ligand-binding site on the surface of human neutrophils. In contrast to ANCA IgM, ANCA IgG also induces an oxidative burst in neutrophils (oxidation of dihydrorhodamine = 91 +/- 15 fluorescence units with anti-PR3 IgG vs 17 +/- 2 with anti-PR3 IgM, p < 0.001). Blockade of the ligand-binding site of Fc gamma RIIa with an antibinding site mAb Fab significantly reduces this ANCA IgG-triggered production of reactive oxygen species (p < 0.01). Similarly, human ANCA bind the ANCA target, engage Fc gamma RIIa, and induce an oxidative burst in neutrophils. The allelic phenotype of Fc gamma RIIa strongly influences the Fc gamma receptor engagement by ligand, and Fc gamma RIIa homozygous donors differ by more than threefold in the quantitative production of reactive oxygen intermediates (ROI) (p < 0.01). Thus, engagement of Fc gamma RIIa by the Fc region of ANCA is one mechanism by which these autoantibodies activate receptor-mediated signal transduction systems in human neutrophils to initiate programs of inflammation and tissue injury. Fc gamma receptor alleles may represent heritable disease risk factors influencing the magnitude of such a process.

Apart from the diagnostic value of anti-neutrophil cytoplasmic antibodies (ANCA), their detailed characterization and that of their corresponding antigens have opened new ways for the exploration of the pathogenesis of primary systemic vasculitis. ANCA are now thought to play an important functional role via activation of phagocytic cells (e.g. polymorphonuclear neutrophils (PMN)). In this study we examined the mechanisms by which ANCA could gain access to proteinase 3 (PR3) in intact PMN, at two levels: ex vivo by analysing the presence of PR3 on the plasma membrane of PMN from patients with ANCA-associated vasculitis, and in vitro by stimulation of PMN using different cytokines, including recombinant tumour necrosis factor-alpha (rhTNF-alpha) and two forms of IL-8 (produced by monocytic and endothelial cells). Using immunocytochemical staining techniques (FACS and immunoelectronmicroscopy) PR3 has been detected on the plasma membrane of PMN from patients with active ANCA-associated vasculitis. However, this phenomenon is also seen in patients with sepsis who do not have ANCA. In addition, TNF-alpha and both forms of IL-8 act synergistically and induce a translocation of PR3 from the intragranular loci to the cell surface of PMN. These results provide strong evidence for the hypothesis that ANCA are directly pathogenic by binding to PR3 which is expressed on the cell surface of primed/activated PMN.

Wegener's autoantigen (WA), a 29 kD multifunctional protein, is the principal target antigen of autoantibodies associated with Wegener's granulomatosis (WG). WA was first identified as proteinase 3 (PR3), which is now known to be identical with myeloblastin and AGP7. Like other lysosomal proteins, WA/PR3 displays enzymatic activity, differentiation factor activity for myeloid precursor cells, and antimicrobial functions. Neutrophilic polymorphonuclear leukocytes (PMN) and a subpopulation of monocytes contain high levels of WA/PR3 in their myeloperoxidase-positive granules. The autoantibodies from WG sera produce a finely granular, centrally accentuated fluorescence pattern on PMN and monocytes and have been designated 'classic' pattern antineutrophil cytoplasmic autoantibodies (cANCA). However, PMN/monocyte activation (in vitro/ex vivo) is associated with the translocation of WA/PR3 on the cytoplasm membrane. WA/PR3 is accessible to the WG-associated autoantibody: cANCA stimulate cytokine-preactivated PMN to produce oxygen radicals and to degranulate. Furthermore, cANCA interfere with the biological functions of WA/PR3 (e.g. inhibition of elastinolytic activity). Hence, cANCA represents not only the best seromarker for WG so far available, but several lines of evidence indicate that the autoantibodies against WA/PR3 play a major role in the pathogenesis of this enigmatic disease.

We studied the presence of proteinase 3 (PR3), myeloperoxidase (MPO) and elastase (HLE) on the plasma membrane of neutrophils in patients with biopsy-proven Wegener's disease (WG), pANCA-positive vasculitis, control patients (SLE, rheumatoid arthritis, ankylosing spondylitis), sepsis patients and healthy donors. We found an overexpression of PR3 on the cell surface of neutrophils in WG, ANCA-associated vasculitis and during infection (sepsis). Thus PR3 becomes accessible to ANCA. Furthermore we detected intracytoplasmic IgG antibodies in PMN from patients with WG by immunoelectron microscopy and direct immunofluorescence. Our findings support the pathophysiological role of ANCA.

Antineutrophil cytoplasmic autoantibodies (ANCA) specific for constituents of neutrophil primary granules and monocyte lysosomes have been demonstrated in various vasculitic disorders. The staining pattern in indirect immunofluorescence microscopy using alcohol-fixed neutrophils as substrate allows distinction among 3 types of ANCA: 1) classic anti-neutrophil cytoplasmic antibody (cANCA, formerly known as ACPA); 2) a type with a perinuclear/nuclear staining pattern produced when alcohol-fixed neutrophils are used as substrate (pANCA); and 3) a mixture of both of the above types (xANCA, also described recently as pANCA). Most cANCA are directed against proteinase 3 ("Wegener's autoantigen"). Some pANCA have specificity for myeloperoxidase and are associated with idiopathic crescentic glomerulonephritis ("renal vasculitis") and other systemic vasculitides exhibiting a paucity of immune deposits in blood vessels. In addition to being a useful serological marker, ANCA appear to be directly involved in the pathogenesis of systemic vasculitis. ANCA can activate cytokine-primed granulocytes and monocytes to undergo a respiratory burst and degranulation. This effect leads to vasculitis through the attachment of these cells to the vascular endothelium primed by cytokine-induced expression of adhesion molecules (E-LAM 1) on the endothelium. Thus, the release of toxic oxygen radicals and lytic enzymes is capable of causing vascular damage. In the present paper we report on the main target antigens and on the history, nomenclature, laboratory methods, and etiopathological implication of ANCA. Additional pathophysiological aspects of ANCA and/or autoreactive T cells and immunoregulatory events are also discussed.

Autoantibodies against neutrophil cytoplasmic antigens (ANCA) produce two major immunofluorescence (IF) patterns on ethanol-fixed granulocytes: the "classical" (centrally accentuated) C-ANCA, associated with Wegener's granulomatosis (WG), and P-ANCA (perinuclear), which mainly occur in renal vasculitis. Rheumatic manifestations are an important clinical finding in systemic vasculitis, often preceding a fulminant course and sometimes imitating various rheumatic disorders. We analyzed the incidence of ANCA in rheumatic patients and looked for the frequency of rheumatic symptoms in systemic vasculitis. In WG (n = 186), we found rheumatic symptoms in 55% (myalgia, 45%; arthritis, 21%); in 90%, rheumatic complaints were associated with active vasculitis. In 730 patients with various rheumatic conditions (eg, 268 rheumatoid arthritis, 130 systemic lupus erythematosis [SLE], 32 sharp-S, 50 ankylosing spondylitis, 43 systemic sclerosis) no C-ANCA were found. On the contrary, the P-ANCA pattern was seen in seven of 62 giant cell arteritis, five of 27 Felty's/Still's syndrome, and four of 130 SLE patients in addition to renal vasculitis (21/74). We demonstrated that 95% of C-ANCA-positive sera react with proteinase 3 (PR3 or myeloblastin). Using monoclonal antibodies, we showed that PR3 is expressed on the plasma membrane of neutrophil granulocytes and monocytes; thus, PR3 autoantigens are accessible for circulating antibodies. The detection of ANCA in sera from vasculitis and other rheumatic diseases is of immunodiagnostic value and provides new insight in the pathogenesis of systemic vasculitides.

To investigate the distribution of proteinase 3, the target antigen of anti-cytoplasmic antibodies (ACPA or C-ANCA), within the organelles of resting normal human polymorphonuclear leukocytes and monocytes, the authors used immunocytochemical techniques on thin frozen sections. To obtain valuable tools for immunolabeling, two murine monoclonal antibodies (MAbs) directed against the ACPA antigen were produced. In neutrophils, the authors observed immunogold label for the ACPA antigen, predominantly in myeloperoxidase-positive azurophil granules, and in smaller amounts on the plasma membrane. In monocytes, the ACPA antigen could be detected in small granules, which occasionally also contained myeloperoxidase, and rare labeling was found on the monocyte membrane. The finding that the ACPA antigen is expressed on the plasma membrane of neutrophils and monocytes, thereby becoming accessible to circulating autoantibodies, supports the supposition that ACPA are not only markers of disease activity, but also are involved in the pathogenesis of Wegener's granulomatosis.

Since proteinase 3 (PR3)-ANCA interact with PR3 on the surface of apoptotic polymorphonuclear neutrophils (PMN) and ingestion of apoptotic PMN is known to modulate macrophage inflammatory reactions, we raised the question whether PR3-ANCA-opsonized apoptotic PMN influence the uptake by macrophages and their state of activation. We therefor analysed the effects of PR3-ANCA-opsonized apoptotic PMN on the uptake process by enzymatic assay. We further investigated the production of TNF-α, IL-10, IL-12 and the secretion of lipid inflammatory mediators (TxB2, leukotriene B4 (LTB4) and prostaglandin E2 (PGE2)) by human monocyte-derived macrophages using FACS and ELISA methods. We show that PMN-opsonization by PR3-ANCA substantially enhances phagocytosis by macrophages and thereby triggers the production of TNF-α and TxB2. These in vitro findings indicate that PR3-ANCA opsonization of apoptotic PMN might be an important mechanism in the pathogenesis of Wegener's granulomatosis (WG), prompting macrophages to produce proinflammatory mediators. These mediators, mainly TNF-α, might prime further PMN leading to perpetuation of the known priming-dependent mechanisms of ANCA action. [ABSTRACT FROM AUTHOR]

TGF-β is a multifunctional cytokine modulating the onset and course of autoimmune diseases as shown in experimental models. The aim of this study was to investigate TGF-β expression in ANCA-associated vasculitis (AAV), and the possible interactions of this cytokine with lysosomal enzymes identified as ANCA autoantigens (e.g. PR3). This included TGF-β effects on the translocation of the lysosomal enzymes to the cell surface of polymorphonuclear neutrophils (PMN), and the presumed activation of non-bioactive, latent TGF-β by these enzymes. Patients with various types of systemic vasculitis (SV) were studied, including three different types of AAV (Wegener's granulomatosis (WG), Churg-Straß syndrome (CSS) and microscopic polyangiitis (MPA)). Regardless of the type of assay applied, the TGF-β1 isoform was found to be overexpressed in SV, including AAV, and to correlate with disease activity as shown for WG. Mean TGF-β1 plasma levels in AAV patients ranged from 8.9 ng/ml (WG) to 13.3 ng/ml (CSS) (control 4.2 ng/ml; P < 0.01), while TGF-β2 levels were not elevated. Flow cytometry analysis showed TGF-β1 to be a potent translocation factor for PR3 comparable to other neutrophil-activating factors such as IL-8. PR3 membrane expression on primed PMN increased by up to 51% after incubation with TGF-β1. PR3 itself was revealed as a potent activator of latent TGF-β, thus mediating bioeffects of this cytokine. These findings, together with other features of TGF-β such as induction of angiogenesis and its strong chemotactic capacity, indicate that TGF-β might serve as a proinflammatory factor in SV, especially in AAV. [ABSTRACT FROM AUTHOR]

It was our purpose to determine the immunodiagnostic value of ANCA directed against BPI in diseases known to he associated with ANCA. such as ANCA-associated vasculitides, inflammatory bowel disease (IBD) and the associated condition primary selerosing cholangitis. The immunoreactivity of recombinant BP1 (rBP1) was established in order to an ELISA specific for rBPI. By means of this assay. BPI-ANCA were assessed in sent of 178 patients with IBD or the associated disorder primary selerosing cholangitis. 112 patients with ANCA-associated vasculitides, arid in sera ol 182 disease and 140 healthy controls. BPI-ANCA were found to he closely associated with IBD and primary selerosing cholangitis (34% and 44% of ANCA-positive sera respectively). By contrast, BPI-ANCA positivity was low t<10%) in the double-negative sera of patients with ANCA-associated vasculitides and in disease and healthy controls. BP1-ANCA appear to constitute an important marker for IBD and primary selerosing cholangitis, but not for the ANCA-associated vasculitides. [ABSTRACT FROM AUTHOR]

In this uncontrolled study 15 patients with ANCA-associated systemic vasculitis, who were poor responders to conventional therapy, were treated with single or multiple courses of intravenous immunoglobulin (IVIG). 30g/day over 5 days. Clinical and serological evaluation was performed before and 4 weeks after IVIG. Six of the 15 patients experienced clinically significant benefit from IVIG. Improvement was confined to single organ manifestations (skin. ENT findings), no improvement was seen with conjunctivitis and scleritis, pericarditis or nephritis. No patient experienced complete remission after IVIG. Repeated courses of IVIG at 4-week intervals were no more effective than single courses. In six anti-proteinase 3 (PR3)-positive patients pretreatment sera were incubated with F(ab')2 fragments of the IVIG preparation in vitro to measure the inhibitory effect of IVIG on tinti-PR3 activity. An inhibition of anti-PR3 activity by 25-70% was observed; this did not correlate with clinical effects. Approximately 40% of patients benefited from IVIG treatment, though complete remission of disease activity did not occur. Neither clinical characteristics nor the inhibitory effect of the IVIG preparation on serum anti-PR3 activity in vitro predicted clinical response to this treatment modality. [ABSTRACT FROM AUTHOR]