人源M2抗原检测M2抗体诊断抗线粒体抗体阴性原发性胆汁性肝硬化

目的 分析抗线粒体抗体（AMA）阴性的原发性胆汁性肝硬化（PBC）患者与AMA阳性PBC患者在临床症状，实验室诊断指标等方面的差异；对比用克隆表达的人源M2抗原建立的酶联免疫吸附试验（ELISA）法测定M2抗体，与经典的间接免疫荧光法测定AMA的敏感性高低。方法 测定63例PBC患者外周血中的AMA与M2抗体。结果 AMA在63例PBC患者中的阳性率为81%。而M2抗体为100%；AMA阴性的PBC患者抗核抗体（ANA），抗平滑肌抗体（ASMA）的阳性率高于AMA阳性的PBC患者，但在临床症状和其他实验室诊断标准上差异并无显著性。结论 酶联免疫吸附试验（ELISA）法检测M2抗体的敏感性高于间接免疫荧光法测定AMA，PBC患者外周血中AMA的阳性与否和疾病并无明显关联。     

急性脑梗死患者抗心磷脂抗体、抗中性粒细胞胞浆抗体与IMT及颈动脉狭窄的相关性

目的 探讨急性脑梗死患者抗心磷脂抗体(ACA)、抗中性粒细胞胞浆抗体(ANCA)对颈动脉内膜中膜厚度(IMT)和颈动脉狭窄的影响.方法 连续纳入首次发病的急性脑梗死(ACI)患者250例,采用酶联免疫吸附法定性检测患者清晨空腹血清中ACA,间接免疫荧光法定性检测ANCA.将所有入选患者分为ACA阳性组、ANCA阳性组和阴性对照组(ACA和ANCA均为阴性),并行颈动脉超声检查,比较三组的IMT、颈动脉狭窄程度.结果急性脑梗死ACA阳性组和ANCA阳性组左、右两侧IMT值高于阴性对照组(P ＜0.001);颅外段颈动脉狭窄率(88.68％和85.71％比54.71％)均高于阴性对照组(P＜0.017).结论 急性脑梗死患者ACA、ANCA与IMT、颈动脉狭窄有关.     

系统性红斑狼疮患者中抗中性粒细胞胞质抗体和细胞因子的关系

目的　探讨抗中性粒细胞胞质抗体 (ANCA)与系统性红斑狼疮 (SLE)血管炎临床特点的关系。检测SLE血管炎患者肿瘤坏死因子 (TNF) α、白细胞介素 (IL) 6等细胞因子的血清水平 ,探讨ANCA与SLE血管炎细胞因子的关系。方法　 6 0例SLE活动期患者和 30名正常对照组均通过间接免疫荧光法 (IIF)检测ANCA与酶联免疫吸附试验 (ELISA)检测抗髓过氧化物酶 (MPO)抗体 (即MPO ANCA) ,观察两组ANCA与抗MPO抗体的阳性率。通过ELISA法检测 30例SLE活动期患者和 30名健康对照者 ,外周血TNT α、白细胞介素 (IL) 6水平。结果　 6 0例SLE患者 1 5例ANCA阳性 ,均为核周型抗中性粒细胞胞质抗体 (pANCA) ,阳性率为 2 5 % ,抗MPO抗体 8例阳性(IIF法ANCA均阳性 ) ,阳性率为 1 3 3% ,健康对照组ANCA及抗MPO抗体均为阴性。病程超过 1年 ,伴有肾炎、浆膜炎、皮肤血管炎组 ,ANCA阳性率高 ,与无相应特点的对照组差异均有显著性 (P <0 0 5 ) ;有关节炎比无关节炎组ANCA阳性率高 (P =0 0 5 )。SLE活动期患者与对照组相比 :SLE组TNF α、IL 6水平较高 (P <0 0 5 )。抗MPO抗体阳性组与抗MPO抗体阴性组相比 :TNF α、IL 6水平升高 ,两组差异有显著性 (P <0 0 5 )。结论　部分SLE病人血清中可检测到 pANCA及抗MPO抗体 ,pANCA与SLE某些     

抗中性粒细胞胞质抗体与系统性红斑狼疮的相关性研究

目的探讨抗中性粒细胞胞质抗体（ANCA）与系统性红斑狼疮（SLE）的相关性及其临床意义。方法收集活动组和非活动组各50例SLE患者的临床和实验室资料,间接免疫荧光（IIF）方法检测患者血清ANCA,AN-CA阳性者加做髓过氧物酶（MPO）、蛋白酶3（PR3）的酶联免疫检测（ELISA）。结果①活动组SLE患者ANCA阳性率（64.0%）高于非活动组（20.0%）及对照组（2.0%）（P均〈0.05）;②ANCA阳性组与阴性组比较,在临床表现（胸膜炎、心包炎、肾损害方面）2、4 h尿蛋白〉0.5 g/d、抗ds-DNA抗体阳性、低补体血症方面差异有统计学意义（P〈0.05）;③ANCA阳性的狼疮肾炎组MPO-ANCA阳性率（71.4%）高于非狼疮肾炎组（25.0%）,P=0.038。结论 ANCA与SLE发病和疾病活动有关,可能是判断SLE病情复发与缓解的一个有用指标;MPO-ANCA可能和狼疮肾炎存在密切相关性。     

溃疡性结肠炎和感染性结肠炎血清学和免疫病理学指标的比较分析

背景：溃疡性结肠炎（UC）与感染性结肠炎（IC）均为结肠性腹泻的常见原因，即使综合临床表现、内镜和组织学检查等表现，仍有部分UC与IC难以鉴别。目的：比较抗中性粒细胞胞浆抗体（ANCA）、CD44v3、CD44v6和转化生长因子（TGF）β1在UC和IC中表达的差异，为两组患者提供有用的鉴别指标。方法：采用间接免疫荧光法（IIF）和酶联免疫吸附法（ELISA）检测血清ANCA和ANCA靶抗原：免疫组化法检测两组患者结肠黏膜CD44v3、CD44v6和TGFβ1的表达。结果：血清ANCA检测UC患者阳性率IIF法为48．1％．ELISA法为33．3％．而IC组均为阴性，两组比较差异有显著性（P〈0．05）；结肠黏膜CD44v3、CD44v6在UC患者表达阳性率分别为68．8％、56．3％，而IC组均阴性，两组比较均有显著差异（P〈0．05）；两组患者结肠黏膜TGFβ1的表达无显著差异（P〉0．05）。结论：血清ANCA和结肠黏膜CD44v3、CD44v6的检测有助于鉴别UC与IC。     

抗中性粒细胞胞浆抗体在肾炎综合征中的检测及其临床意义

目的　探讨检测抗中性粒细胞胞浆抗体 (ANCA)及其靶抗原在肾炎综合征中的临床意义。方法　应用间接免疫荧光 (IIF)法检测 10 0例肾炎综合征患者血清抗中性粒细胞胞浆抗体 ,对其阳性的 2 9例用酶联免疫吸附试验 (ELISA )检测靶抗原髓过氧化物酶 (MPO)和蛋白酶 3(PR3 )。结果　IIF检测肾炎综合征ANCA阳性率为 2 9% ,其中胞浆型 10 %、核周型 19%。急进型肾炎、狼疮性肾炎、紫癜性肾炎阳性率分别为 5 6%、2 0 %和 15 %。ELISA急进性肾炎和紫癜性肾炎大多数识别靶抗原MPO ,狼疮性肾炎ANCA不识别MPO或PR3。结论　ANCA在急进性肾炎和狼疮性肾炎中阳性率较高 ,检测ANCA对判断狼疮性肾炎活动及疗效具有参考价值     

ANCA水平检测对判断系统性红斑狼疮活动性和伴肺间质病变的检测意义

目的探讨抗中性粒细胞胞质抗体（ANCA）在系统性红斑狼疮（SLE）伴肺间质病变（ILD）中的临床意义。方法用间接免疫荧光法（IIF）及免疫印迹法方法，检测97例SLE患者血清中的ANCA、抗dsDNA抗体、多种自身抗体及补体。采用全胸片及肺高分辨率CT（HRCT）检查，了解97例SLE患者伴ILD的情况。结果①97例SLE患者26例ANCA阳性，均为核周型（pANCA），阳性率为27％。（2）ANCA阳性组患者的抗dsDNA抗体的增高、补体（C3、C4）的下降及血沉（ESR）增高与ANCA阴性组相比，差异均有统计学意义（P〈0．01）。（3）6例ANCA阳性组患者，HRCT显示其中20例伴ILD（77％），71例ANCA阴性组患者，伴ILD30例（42％），ANCA阳性组的ILD发病率明显高于阴性组，两组差异有统计学意义（P〈0．01）。结论ANCA阳性的SLE患者。对判断SLE活动性及伴ILD具有一定的临床价值。     

蛋白芯片技术对自身免疫性抗体的检测及评价

目的 探讨蛋白芯片技术检测自身抗体的临床价值。方法 用酶联免疫吸附试验（ELISA）、蛋白芯片法检测抗dsDNA、抗Ro-60／SSA、抗Ro-52／SSA、抗SSB、抗Jo-1、抗磷脂IgG抗体．用间接免疫荧光法（IIF）、蛋白芯片法检测抗核抗体（ANA）,分别统计两种方法检测均阳性、均阴性和单阳性的标本数目．并进行评价。结果 芯片法检测ANA的灵敏度为89％、特异度为60％．芯片法对其他6种自身抗体检测的灵敏度为70．0%～87．5%、特异度为92．7％～98．9％。结论 蛋白芯片法检测自身抗体与常规方法比较,特异度较高,有待进一步改善技术提高其灵敏度。     

三种自身抗体联合检测对狼疮疾病活动和狼疮肾炎的价值

目的探讨联合检测抗C1q抗体、抗核小体抗体(AnuA)和抗dsDNA抗体对狼疮活动和狼疮肾炎(LN)的价值。方法 90例系统性红斑狼疮(SLE)分为疾病活动和疾病稳定组、LN和非LN组, 酶联免疫吸附试验(ELISA)检测血清抗C1q抗体和AnuA水平,间接免疫荧光法比较三抗体单个和联合对疾病活动和LN的价值。结果抗C1q抗体、AnuA和抗dsDNA抗体阳性对疾病活动的敏感性分别为 71．4％、75．0％和66．1％,特异性分别为75．5％、70．6％和88．2％;抗dsDNA抗体阴性患者分别有36．7％抗 C1q抗体阳性和26．5％AnuA阳性。疾病活动组三抗体阳性率和抗体水平显著高于疾病稳定组;三抗体与 SLE疾病活动指数(SLEDAI)、血沉(ESR)、IgG、球蛋白水平显著正相关,与C3、C4及白蛋白水平显著负相关。LN组三抗体水平显著高于非LN组。结论三抗体都是狼疮疾病活动的指标,都与LN有关,联合检测可以提高疾病活动检出率。     

抗PR3抗体和抗MPO抗体的检测及临床研究

目的探讨抗蛋白酶-3(PR3)抗体、抗髓过氧化物酶(MPO)抗体和抗中性粒细胞胞质抗体(ANCA),在系统性血管炎患者中的检测及临床意义。方法对251例临床确诊为系统性血管炎和其他自身免疫性疾病患者血清,应用酶联免疫吸附试验(ELISA)检测抗PR3抗体和抗MPO抗体;用间接免疫荧光法(IIF)检测ANCA,并进行回顾性分析。结果①251例系统性血管炎患者与非血管炎病人的检测,经χ2检验,P<0.01,差异均有非常显著性。②33例韦格纳肉芽肿病(WG)患者主要表现为PR3和颗粒型抗中性粒细胞胞质抗体(cANCA)阳性均为22例,阳性率为67%;非血管炎病人,27例溃疡性结肠炎(UC)患者检测MPO和核周型抗中性粒细胞胞质抗体(pANCA)阳性分别为13和14例,阳性率分别是48%和52%;104例SLE患者检测MPO和pANCA阳性分别为19例、24例,阳性率分别为18%和23%。③ELISA法和IIF法阳性率,经χ2检验差异无显著性(P>0.05)。结论PR3、MPO抗体作为系统性血管炎的一种敏感标记抗体,有利于该疾病的早期治疗。     

Absence of ANCA in Behçet's syndrome with large vessel involvement

The aim of this study was to examine the prevalence of anti-neutrophil cytoplasmic antibodies (ANCA) in patients with Behcet's syndrome (BS) with large vessel involvement. The sera of 48 consecutive patients with BS with large vessel involvement, seven patients with Wegener granulomatosis (WG), and 10 healthy staff were studied for the presence of the cytoplasmic (c) and perinuclear (p) pattern of ANCA by indirect immunofluoresance (IIF). The sera were also examined for antibodies against proteinase 3 (anti-PR3) and myeloperoxidase (anti-MPO) by enzymelinked immunosorbent assay (ELISA). None of the sera from the patients with BS and healthy controls had detectable ANCAs, while all positive control sera from patients with WG showed ANCA positivity in some form. This study confirms that there are no detectable ANCAs in patients with BS with large vessel involvement by IIF and ELISA tests.     

Low seroprevalence and poor specificity of antineutrophil cytoplasmic antibodies in tuberculosis

OBJECTIVES: Recently published findings suggested that antineutrophil cytoplasmic antibodies (ANCA), particularly those with a cytoplasmic (C-ANCA) labelling pattern and targeting proteinase 3 (anti-PR3), might be markers of tuberculosis (TB). This is a critical issue, because C-ANCA/anti-PR3 were considered to be a highly specific hallmark of Wegener's granulomatosis or microscopic polyangiitis and because TB may clinically mimic Wegener's granulomatosis. We therefore undertook a study with the aim of investigating further the prevalence and specificity of ANCA in TB. METHODS: We evaluated serum samples from 67 patients diagnosed with culture-proven TB and 10 previously untested control samples from patients known to be ANCA positive (four Wegener's granulomatosis and two microscopic polyangiitides) or negative. All 77 sera were screened for ANCA using commercially available indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA) for anti-PR3 and antimyeloperoxidase (MPO). IIF-positive and anti-PR3- and anti-MPO-negative sera were also tested for bactericidal/permeability-increasing protein, lactoferrin, elastase and cathepsin G specificities with commercially available ELISA. RESULTS: IIF detected ANCA in seven (10%) of the TB sera, including three C-ANCA and four atypical perinuclear-labelling ANCA. Only one IIF-negative specimen was anti-PR3 positive in ELISA. ANCA testing of the control sera yielded IIF and ELISA results concordant with previous findings, except for one borderline ELISA. CONCLUSION: Our results indicate that TB is associated with low ANCA seroprevalence and poor specificity, with no test serum showing combined C-ANCA/anti-PR3 activity. In a clinical setting of Wegener's granulomatosis/TB mimicry, such combined reactivity would seem to be more suggestive of Wegener's granulomatosis.     

Autoantibodies to proteinase 3 and myeloperoxidase in systemic sclerosis

OBJECTIVE: We evaluated the prevalence and clinical significance of proteinase 3 (PR3-) and myeloperoxidase (MPO-) antineutrophil cytoplasmic antibodies (ANCA) in 115 patients with systemic sclerosis (SSc, scleroderma). METHODS: Sera were assayed by 2 independent centers, which used indirect immunofluorescence (IIF) and direct ELISA as screening tests. Inhibition-ELISA for PR3- and MPO-ANCA and PR3 capture-ELISA experiments were also performed. The clinical features of the ANCA positive were compared with those of the ANCA negative scleroderma patients. RESULTS: The IIF test revealed 5 P-ANCA positive sera (4.34%). Surprisingly, by ELISA 2 of these were PR3-ANCA positive, one was MPO-ANCA positive, and 2 were both PR3- and MPO-ANCA positive. In addition, 3 IIF negative sera were ELISA positive, 2 for PR3- and one for MPO-ANCA. ELISA results were confirmed by fluid phase inhibition experiments. Only 2 out of the 6 PR3-direct ELISA positive sera were positive by PR3-capture ELISA at low titers. Neither PR3- nor MPO-ANCA were significantly associated to any clinical feature of patients with SSc. CONCLUSION: As well as the previously described MPO-ANCA, even PR3-ANCA may be detected in some sera from patients with SSc. The IIF pattern and the negative results obtained with PR3-capture ELISA suggest that different epitopes from those recognized by vasculitis sera might be involved with PR3-ANCA in SSc, and show the importance of combining IIF and ELISA tests for ANCA detection.     

Prevalence of antineutrophil cytoplasmic antibodies in patients with various pulmonary diseases or multiorgan dysfunction

OBJECTIVE: To determine the prevalence of antineutrophil cytoplasmic antibodies (ANCA) in patients with diseases that may mimic systemic vasculitides, such as severe multiorgan dysfunction (MOD) and parenchymal pulmonary disorders. METHODS: We conducted a prospective study of patients with MOD admitted to the medical intensive care unit and patients with various lung diseases seen at the outpatient pulmonary clinic of a tertiary care hospital. Patients with a documented diagnosis of Wegener's granulomatosis (WG) served as positive controls. ANCA were determined in serum samples from each patient by a combination of indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assays (ELISAs) for antibodies to proteinase-3 and myeloperoxidase (anti-MPO). RESULTS: Ninety-nine patients with MOD, 29 outpatients with various lung disorders, and 18 patients with WG were included in the study. ANCA were detected by IIF alone in 16% (15/96) of patients with nonvasculitic MOD and 17% (5/29) of outpatients with various pulmonary disorders. The majority of the positive IIF specimens from each group displayed an atypical IIF pattern (73% and 80%, respectively). Only 1 specimen from patients with nonvasculitic disorders was positive for anti-MPO. ANCA by both IIF and ELISA were detected in 78% (12/14) of control patients with WG. CONCLUSION: Detection of ANCA by the combination of IIF and antigen-specific assays for proteinase 3 and myeloperoxidase in diseases that mimic systemic vasculitides is highly specific for WG, microscopic polyangiitis, and Churg-Strauss syndrome.     

Anti-proteinase 3 antibodies in diffuse systemic sclerosis (SSc) with normotensive renal impairment: is it suggestive for an overlapping between SSc and idiopathic vasculitis?

OBJECTIVE: To test the prevalence of anti-neutrophil cytoplasmic antibodies (ANCA) in systemic sclerosis (SSc) and to verify a possible association of ANCA with normotensive renal involvement in SSc. PATIENTS AND METHODS: 51 patients affected by SSc, 35 with diffuse scleroderma (dSSc) and 16 with limited scleroderma (lSSc), were tested for ANCA by indirect immunofluorescence (IIF) on human ethanol and formalin-acetone-fixed granulocytes (before and after DNase treatment), by conventional enzyme linked immuno-sorbent assay (ELISA) and by capture-ELISA. RESULTS: Six out of 51 selected SSc patients had ANCA by IIF (11.7%) and five presented a perinuclear/nuclear atypical ANCA pattern. In all cases we only found anti-proteinase3 (aPR3) antibodies. All ANCA positive patients had diffuse form of SSc (17.1%), all were anti-Scl70 positive (aScl70), five patients had proteinuria, three had microscopic haematuria. All ANCA positive patients were normotensive with normal renin plasma levels, the mean erythrocyte sedimentation rate (ESR) was higher in this group compared to the other SSc patients. CONCLUSIONS: Our study shows that aPR3 is not rare in dSSc. According to the clinical and serological findings and to the recent literature, we can hypothesise that when ANCA are found in SSc, an overlapping of scleroderma with systemic necrotizing vasculitis should be suspected.     

Antineutrophil Cytoplasmic Antibody in Patients with Primary Sjo¨gren’s Syndrome

The incidence, specificity and clinical significance of positivity for serum antineutrophil cytoplasmic antibody (ANCA) was investigated in 60 patients with primary Sj?gren's syndrome (SjS). The indirect immunofluorescence (IIF) technique and an enzyme-linked immunosorbent assay (ELISA) were used to measure ANCA. Purified myeloperoxidase (MPO), lactoferrin (LF), cathepsin-G (CTG) and elastase (HLE) served as ANCA antigens for the ELISA. Ten (16.7%) of the 60 SjS patients showed positivity by IIF for perinuclear, but not cytoplasmic, ANCA. Four of the 60 sera were shown to be positive for LF, four for MPO, 0 for CTG and 0 for HLE by ELISA. There was no correlation between ANCA positivity and clinical features. ANCA in patients with SjS might be an epiphenomenon of polyclonal B-cell activation.     

Bactericidal/permeability-increasing protein and cathepsin G are the major antigenic targets of antineutrophil cytoplasmic autoantibodies in systemic sclerosis

OBJECTIVE: To study the prevalence and antigenic specificity of antineutrophil cytoplasmic autoantibodies (ANCA) in patients with systemic sclerosis (SSc). METHODS: Sera from 68 patients with SSc were screened for ANCA by indirect immunofluorescence (IIF) assay and for antibodies to myeloperoxidase (MPO) by ELISA. All sera positive for ANCA on IIF were analyzed for reactivity against antigenic targets other than MPO [bactericidal/permeability-increasing protein (BPI), cathepsin G, lysozyme, elastase, PR3, and lactoferrin]. Twenty-three sera negative for ANCA were also tested for antibodies to BPI and cathepsin G using ELISA. RESULTS: The study included 33 patients with diffuse and 35 with limited SSc. ANCA was detected in 24 of the 68 sera (35.3%). In these 24 sera the antigenic targets were BPI in 14, cathepsin G in 13, and MPO in 8. Sera of 11 patients had reactivity against both BPI and cathepsin G. In sera, that were negative for ANCA, antibodies to BPI (4/23), cathepsin G (3/23), and MPO (1/44) were found in a small proportion of patients. Patients with antibodies to BPI had lower skin score, whereas no patient with antibodies to MPO had renal disease. CONCLUSION: BPI and cathepsin G are the major antigenic targets of ANCA seen in patients with SSc. Patients with antibodies to BPI had lower skin scores.     

Prediction of relapses in Wegener's granulomatosis by measurement of antineutrophil cytoplasmic antibody levels: a prospective study

OBJECTIVE: Prediction of relapses in Wegener's granulomatosis (WG) by measuring levels of antineutrophil cytoplasmic antibodies (ANCA) directed against proteinase 3 (PR3) or myeloperoxidase (MPO) remains a controversial issue. To assess the value of serial quantification of ANCA by indirect immunofluorescence (IIF) and antigen-specific enzyme-linked immunosorbent assay (ELISA) for monitoring disease activity in patients with WG, a prospective observational study was conducted in patients with WG attending an outpatient clinic in the Netherlands. METHODS: One hundred patients with WG (85 with PR3-ANCA, 15 with MPO-ANCA) were studied prospectively from 1996 to 1998. Serum samples were obtained and analyzed every 2 months for ANCA levels. Disease activity was prospectively assessed without knowledge of the ANCA levels. RESULTS: Relapses occurred in 37 of 100 patients (37%). Thirty-four (92%) of the 37 patients showed a rise in the level of ANCA preceding their relapse, as detected by ELISA or IIF. The predictive value of an increase in ANCA titers for relapse was 57% (17 of 30) for cytoplasmic/classic ANCA (cANCA; by IIF), 71% (27 of 38) for PR3-ANCA (by ELISA), and 100% (3 of 3) for MPO-ANCA (by ELISA). The predictive value of a rise in ANCA as measured by ELISA or IIF did not substantially improve following concomitant measurement of the IgG3 subclass of PR3-ANCA. Forty-three percent of patients who showed a rise in cANCA (by IIF) and 29% with a rise in PR3-ANCA (by ELISA) did not subsequently experience a relapse. CONCLUSION: Serial measurement of ANCA levels is valuable for the early prediction of relapses in patients with WG.     

Prevalence of antineutrophil cytoplasmic autoantibodies in patients with tuberculosis

OBJECTIVE: To determine the prevalence of antineutrophil cytoplasmic autoantibodies (ANCA) in sera of patients with tuberculosis compared with healthy control subjects and a group of patients with atopic asthma. METHODS: The presence of ANCA was examined in patients with tuberculosis, and in asthmatic patients and healthy subjects as control groups, by means of indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA) to detect anti-proteinase 3 (PR3-ANCA) and antimyeloperoxidase (MPO-ANCA) antibodies. RESULTS: ANCA were present in 20 (44.4%) of 45 tuberculosis patients by IIF (16 c-ANCA, four p-ANCA) and in 18 (40%) patients by ELISA (15 PR3-ANCA, three MPO-ANCA). High odds ratios for ANCA positivity were observed for tuberculosis patients when compared with both control groups. ANCA results were not related to the category of tuberculosis, stage of disease, presence of concomitant diseases or pharmacotherapy. CONCLUSIONS: As many clinical similarities between tuberculosis and Wegener's granulomatosis exist, we propose that a positive ANCA test in patients living in countries with a high prevalence of tuberculosis must be carefully interpreted as indicative of systemic vasculitis, especially when no signs of extrapulmonary involvement occur.