Place of human amniotic membrane immunoblotting in the diagnosis of autoimmune bullous dermatoses

Background Fine analysis of antiskin autoantibodies can contribute to the differential diagnosis of autoimmune bullous dermatoses. Objectives To develop a high‐performance immunoblotting method using human amniotic membrane as the antigen source, and to compare it with current laboratory methods. Methods Sera from 113 patients were tested by immunoblotting (IB), rat and monkey oesophagus and salt‐split skin indirect immunofluorescence (IIF), and enzyme‐linked immunosorbent assay (ELISA) quantification of anti‐BP180‐NC16a and anti‐BP230, or antidesmoglein (Dsg) 1 and 3 antibodies. There were 56 cases of bullous pemphigoid (BP), 22 cases of mucous membrane pemphigoid (MMP), eight cases of epidermolysis bullosa acquisita (EBA), two cases of bullous systemic lupus erythematosus (BSLE), 17 cases of pemphigus vulgaris (PV), and four cases each of pemphigus foliaceus (PF) and paraneoplastic pemphigus (PNP). Results In BP, the three methods had similar sensitivity (84–89%) for both anti‐BP180‐NC16a and anti‐BP230 antibody detection. In MMP, autoantibodies (mainly directed against BP180 or laminin 332 subunits) were detected in 77% of patients by IB, compared with only 9% by IIF on rat and monkey oesophagus and 36% on salt‐split skin, and 14% by anti‐BP180‐NC16a and anti‐BP230 ELISA. In patients with pemphigus, ELISA had 92% sensitivity for anti‐Dsg1 and 3, but IB and rat bladder IIF were necessary to confirm PNP by revealing specific and rare patterns (antidesmoplakin I/II, antienvoplakin and antiperiplakin antibodies). IB also revealed anticollagen VII antibodies in 60% of patients with EBA and BSLE, and antibodies to BP180, BP230 and Dsg3 in a few patients who were negative using the other two techniques. Conclusion Amniotic membrane immunoblotting is an interesting diagnostic tool for bullous diseases, as the entire panel of autoantibodies can be detected with a single extract. This method improves the identification of complex and heterogeneous autoimmune processes in conjunction with IIF and ELISA, and is particularly useful for MMP characterization.     

Correlation of autoantibodies against BP180/BP230 in response to topical corticosteroids in patients with bullous pemphigoid

Topical steroids are effective in treating bullous pemphigoid (BP). Autoantibodies against BP180 are related to disease activity, but correlation of these autoantibodies with response to topical steroid therapy has not yet been clearly evaluated. We investigate the usefulness of close and early monitoring of autoantibodies against BP180 and BP230 for assessment of response to therapy and early detection of therapeutic failure in BP patients treated topically. In eight BP patients under treatment with topical or systemic steroid therapy we retrospectively evaluated clinical course and autoantibodies against BP180 and BP230 as well as indirect immunofluorescence titres (IIF). Data were included at diagnosis, during hospitalization and follow‐ups. Autoantibodies against BP180 parallel disease activity in all topically and as well as systemically treated patients. Autoantibodies against BP230 correlated in five out of eight patients. Autoantibodies directed against BP180 and, to a lesser degree, against BP230 correlate with the clinical course of topically treated BP patients. Monitoring autoantibodies against BP180 is a useful tool to evaluate the efficacy of topical therapy in BP.     

Bullous pemphigoid: serum antibody titre and antigen specificity

Abstract 2 antigens have been identified as possible targets for autoantibody depositions in bullous pemphigoid: a 230-kD protein (BP230) and a 180-kD protein (BP180). We studied the relationship of these 2 antigens with the immunofluorescence determined serum antibody titre. 2 groups of bullous pemphigoid patients were selected on the basis of immunoblot-determined antibody specificity. One group (13 patients) had antibody specificity for BP230 and not for BP180, while the other group (9 patients) had antibody specificity for BP180 and not for BP230. The immunofluorescence titres of the circulating antibodies determined on monkey oesophagus substrate displayed, for the BP230-specific group, a mean of 1:1102. The maximal observed titre was 1:5120. The mean titre in the BP180-specific group was only 1:29, with a highest titre of only 1:160. This result suggests that in routine indirect immunofluorescence of bullous pemphigoid sera, the contribution of the BP180-specific antibodies to the total anti-epidermal basement membrane zone antibody titre is relatively much lower than that of the BP230-specilic antibodies. Thus, at high dilutions, only the BP230-speeific antibodies contribute to the overall indirect immunfluorescence titre.     

Autoantibodies to basement membrane proteins BP180 and BP230 are commonly detected in normal subjects by immunoblotting

Autoantibodies to basement membrane proteins BP180 and BP230 are characteristic of bullous pemphigoid and other subepidermal immunobullous disorders. These antibodies are, however, reported in other pruritic dermatoses, non-bullous disorders and non-cutaneous disease. Few studies have assessed basement membrane antibodies in normal subjects; antibody prevalence in this population is not clear. This study aims to examine basement membrane zone antibodies in normal middle-aged to elderly subjects. Sera from 61 healthy subjects (majority age 50–70 years) were assessed by immunoblot, indirect immunofluorescence and enzyme-linked immunosorbent assay. Ninety-one bullous pemphigoid patients acted as positive controls. Antigenic target, antibody class and titre were examined; sera binding BP180 were assessed for reactivity to the non-collagenous 16A (NC16A) domain. Thirty-six normal subjects (59%) had antibodies to either BP180 or BP230 on immunoblot analysis. BP180 was the commonest target antigen, detected in 35 subjects; binding to the immunodominant NC16A domain was not detected. Immunofluorescence was positive in three subjects. Of the bullous pemphigoid sera, 88% were positive on immunoblot or immunofluorescence; a higher frequency had antibodies against BP230. In conclusion, significant numbers of normal healthy subjects have circulating autoantibodies to basement membrane proteins, chiefly BP180 detectable by immunoblot, but these do not bind the NC16A domain.     

Case of localized bullous pemphigoid with unique clinical manifestations in the lower legs

We report the case of a 71-year-old Japanese woman who presented with persistent band-like erosions in the lower legs. Histological examination suggested subepidermal blister formation. Direct and indirect immunofluorescence studies revealed tissue-deposited and circulating immunoglobulin G autoantibodies against the basement membrane. Western blotting revealed autoantibodies to BP230, but not to BP180. Based on these findings, the patient was diagnosed as having a localized type of bullous pemphigoid. We suggest that the unique clinical manifestations in this patient could be attributable to bacterial or fungal infection, and/or mechanical trauma, such as the pressure of her socks.     

Absence of anti-BP180 antibodies in mothers of infants with bullous pemphigoid

BACKGROUND: It is not clear whether bullous pemphigoid (BP) of infancy is linked to maternal transmission of pathogenic autoantibodies. Objectives To search for anti-BP180 antibodies in the sera of infants with BP and their mothers, using sensitive and specific methods. METHODS: Four infants (<6 months) with BP and their mothers were tested for anti-BP180 antibodies by indirect immunofluorescence, immunoblotting and enzyme-linked immunosorbent assay (ELISA). RESULTS: We found anti-BP180 antibodies in the sera of the four infants with all methods. These antibodies reacted with the extracellular domain NC16A. In the serum of their mothers we found 180 and 160 kDa proteins, each in one case, but indirect immunofluorescence and ELISA were negative, suggesting the absence of anti-BP180 autoantibodies reacting with the extracellular domain NC16A. CONCLUSIONS: BP of infants is not due to maternofetal transmission of pathogenic autoantibodies. Other hypotheses for the pathophysiology of BP are discussed.     

Detection of anti-BP180NC16a and anti-BP230 autoantibodies in blister fluid of patients with bullous pemphigoid: the first survey in Greece

Bullous pemphigoid (BP) is an acquired bullous disease with an increasing prevalence among elderly people worldwide, including in Greece. Blister formation in most patients with BP is caused by autoantibodies against structural components of the basement membrane zone of the skin, predominantly BP180NC16a and BP230 antigens on the hemidesmosome adhesion complex. Routine diagnostic methods such as histological examination and direct and indirect immunofluorescence are combined to determine diagnosis. In this study, an ELISA was used to measure levels of both anti-BP180NC16A and anti-BP230 autoantibodies in the blister fluid of 13 patients with newly diagnosed BP, before starting treatment. The aim of the study was to evaluate this method as a diagnostic tool in BP. Our results indicate that blister-fluid examination by ELISA can be a useful tool to diagnose bullous pemphigoid, especially in elderly patients who refuse biopsy or have poor venous access.     

IgA autoantibodies in the pemphigoids and linear IgA bullous dermatosis

Please cite this paper as: IgA autoantibodies in the pemphigoids and linear IgA bullous dermatosis. Experimental Dermatology 2010; 19: 648–653. Background: Patients with bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and pemphigoid gestationis (PG) have IgG antibodies against BP180 and BP230, components of the hemidesmosomes. Patients with linear IgA bullous dermatosis (LABD) have IgA autoantibodies against a 97/120‐kDa protein which is highly homologous to a shedded fragment of the BP180‐ectodomain. Objectives: The aim of our study was to determine the incidence of IgA autoantibodies directed against BP180/BP230 in the pemphigoids and LABD and to determine the antigenic regions that are targeted by IgA autoantibodies. Methods: Utilizing baculovirus‐expressed recombinant BP180 and BP230 proteins, we performed immunoblot analyses for IgA reactivity of sera from patients with BP (n = 30), MMP (n = 10), PG (n = 6), LABD (n = 6) and from control patients with non‐related pruritic dermatoses (n = 8). Results: IgA reactivity against BP180 and/or BP230 was detected in 19/30 of the BP, in 7/10 of the MMP, in 6/6 of the LABD and in 3/6 of the PG sera, respectively, but not in the control group. In all subgroups, the major antigenic site recognized by IgA antibodies was located within the NH₂‐terminus of the BP180‐ectodomain, but only a minority of the sera showed also IgA reactivity against the BP180‐NC16a‐domain. IgA reactivity against the central domain of BP180 was more frequently seen than against its COOH‐terminus. IgA against the COOH‐ and NH₂‐terminus of BP230, respectively, was detected in 6/30 of the BP, 1/10 of the MMP, 1/6 of the LABD and 0/8 control sera. Conclusion: IgA reactivity against BP180 and/or BP230 is a common finding in the pemphigoids.     

Immunoglobulin E and bullous pemphigoid

Clinical features and histological findings in bullous pemphigoid (BP) suggest a Th2-oriented inflammatory reaction, especially in the early stages of the disease. Elevated total serum IgE levels, blood eosinophilia, and elevated serum levels of different soluble inflammatory Th2 response mediators have been described in large cohorts of patients with classic clear-cut BP manifestations. Direct immunofluorescence, indirect immunofluorescence, and anti-BP230 and anti-BP180 IgE ELISA testing show self-reactive IgE autoantibodies in a consistent number of BP patients. Both IgE autoantibodies and a Th2-oriented immune response may play a role in the initial phases of BP and atypical cases of BP, such as severe erythematous and urticarial forms of BP, as well as blister formation. Two recently reported experimental murine models employing IgE autoantibodies against BP180 have been reported and the successful treatment of bullous pemphigoid with the anti-IgE antibody, omalizumab, supports the roles played by IgE autoantibodies in BP pathogenesis.     

Bullous Pemphigoid Associated with Shy-Drager Syndrome

We report a patient with Shy-Drager syndrome who developed multiple tense blisters mainly on the extremities. Circulating anti-basement membrane zone autoantibodies were detected by the indirect immunofluorescence method. Immunoblot analysis using normal human epidermal extracts demonstrated that this patient's serum reacted only with 230 kD bullous pemphigoid antigen (BPAG1). Concerning the pathoetiology of the association of bullous pemphigoid and Shy-Drager syndrome, we discuss a sequence similarity between BPAG1 and dystonin, a candidate gene for dystonia musculorum.     

A Case of Chronic Bullous Disease of Childhood That Was Reactive to the Antigen of 120 kDa (LAD-1)

Chronic bullous disease of childhood (CBDC) is an autoimmune blistering disease that is characterized by Immunoglobulin A (IgA) deposits at the basement membrane zone. IgA autoantibodies (aAbs) from the serum of patients with CBDC react with antigens of 97 kDa (LABD97) and 120 kDa (LAD-1), and both of which are fragments of the extracellular domain of bullous pemphigoid 180 (BP180, type XVII collagen). The CBDC sera reacts with the immunodominant NC16a domain of BP180, which is the major region recognized by IgG aAbs in patients with bullous pemphigoid. A five-year-old boy presented with multiple pruritic tense blisters on the umbilical and inguinal areas for six weeks. The direct immunofluorescence of the perilesional area demonstrated linear deposits of IgA at the basement membrane zone. Using immunoblotting and an enzyme linked immunosorbent assay (ELISA), we identified the IgA aAbs reactive to antigens with a molecular weight of 120 kDa (LAD-1), which is a fragment of the extracellular domain of BP180.     

Bullöses Pemphigoid

Pemphigoid diseases are a group of autoimmune disorders characterized by subepidermal blistering and autoantibodies against structural proteins of the dermal-epidermal junction. In bullous pemphigoid, the most common subepidermal blistering autoimmune disease, antibodies are directed against the hemidesmosomal antigens BP180 (collagen type XVII) and BP230. Bullous pemphigoid typically presents with severe pruritus and tense blisters accompanied by erosions and crusts in elderly patients. Diagnostic landmarks are the detection of linear IgG and/or C3 deposits at the dermo-epidermal junction by direct immunofluorescence microscopy of a perilesional biopsy and the detection of serum autoantibodies by indirect immunofluorescence microscopy on human salt-split skin and ELISA employing recombinant immunodominant fragments of BP180 and BP230. Treatment options include topical (class IV) and/or systemic corticosteroids, frequently combined with immunomodulatory agents like dapsone and tetracyclines or immunosuppressants such as methotrexate and azathioprine.     

Case of bullous pemphigoid coexisting with anti‐desmoglein autoantibodies

A 79‐year‐old Japanese woman had clinical and histopathological features of bullous pemphigoid, while direct immunofluorescence test revealed C3 and immunoglobulin G depositions in the lower cell surfaces of the epidermis in addition to those in the dermoepidermal junction. Chemiluminescent enzyme immunoassays were positive for desmoglein‐1 and ‐3 antibodies in addition to anti‐BP180 antibodies. In an immunoblotting study, antibodies against both 180‐kDa bullous pemphigoid antigen and 130‐kDa pemphigus vulgaris antigen were detected. Based on these results, bullous pemphigoid coexisting with anti‐desmoglein autoantibodies was diagnosed in this case.     

盐裂皮肤间接免疫荧光技术在大疱性类天疱疮诊断中的价值评估

目的:评价盐裂皮肤间接免疫荧光（IIF-SSS）在大疱性类天疱疮（BP）诊断中的价值。方法:采用单中心临床回顾性研究。纳入2013年1月至2019年1月在中国医学科学院皮肤病医院就诊的初诊BP患者163例,对照组404例,包括天疱疮161例、湿疹67例、药疹26例、多形红斑23例、结节性痒疹18例等。于患者用药前采血,...     

嗜酸性粒细胞相关因子在大疱性类天疱疮发病机制中的研究进展

 大疱性类天疱疮(BP)是一种常见的自身免疫性大疱性疾病。一直以来研究者认为针对半粒体抗原BP180和BP230的IgG型自身抗体是BP的主要发病机制。近年来发现,嗜酸性粒细胞以及IgE型自身抗体在BP的发病机制中也起着重要作用,嗜酸性粒细胞通过脱颗粒,释放细胞因子、趋化因子,抗原提呈及调节凝血功能参与BP发病。本文综述近年来嗜酸性粒细胞相关因子在BP中作用研究进展,为靶向嗜酸性粒细胞治疗BP提供思路。     

IgG autoantibodies from a lichen planus pemphigoides patient recognize the NC16A domain of the bullous pemphigoid antigen 180

Lichen planus pemphigoides (LPP) most likely encompasses a heterogeneous group of subepidermal autoimmune blistering disorders occurring in association with lichen planus. We describe the case of a 49-year-old patient with features characteristic of LPP. Direct immunofluorescence microscopy studies demonstrated linear deposits of C3 along the cutaneous basement membrane, while circulating IgG autoantibodies directed against the epidermal side of skin separated by 1 M NaCl were detected. The patient's serum contained IgG autoantibodies immunoblotting a recombinant form of bullous pemphigoid antigen 180 (BP180), but not the COOH-terminus of BP230. By using deletion mutants, it was found that IgG reactivity was restricted to the NC16A domain of BP180, the region harboring the major antigenic sites targeted by IgG autoantibodies from patients with the bullous pemphigoid group of disorders. Our findings provide support to the idea that a subset of patients with LPP have a distinct form of bullous pemphigoid associated with lichen planus.     

Relapse‐associated autoantibodies to BP180 in a patient with anti‐p200 pemphigoid

Anti‐p200 pemphigoid and bullous pemphigoid (BP) are autoimmune subepidermal blistering diseases characterized by autoantibodies to a 200‐kDa dermal antigen (p200) and two hemidesmosomal proteins (BP180 and BP230), respectively. We report a 70‐year‐old man with haemorrhagic blisters, widespread crusted erosions, and the immunopathological characteristics of anti‐p200 pemphigoid. Treatment with doxycycline, topical corticosteroids and immunoadsorption led to rapid clinical remission. However, 19 weeks later, a relapse occurred with generalized itchy urticarial erythema and tense blisters. At this time, both strong dermal and epidermal IgG staining was detected by indirect immunofluorescence microscopy on salt‐split skin, and autoantibodies against both p200 and the 16th noncollagenous (NC16A) domain of BP180 were found. Interestingly, the relapse was associated not only with the detection of autoantibodies to a second autoantigen (BP180), but also with an altered clinical phenotype. This case was a unique occasion to directly monitor the emergence of intermolecular epitope spreading during the course of an autoimmune bullous disorder.     

BP180NC16a-ELISA检测大疱性类天疱疮多中心随机双盲对照试验

目的 探讨BP180抗体诊断试剂盒检测大疱性类天疱疮（BP）的灵敏度和特异度。方法 多中心随机双盲平行对照临床试验。使用BP180抗体诊断试剂盒（ELISA）检测106例临床已经确诊的活动期BP患者和106例对照人群（含非BP的其他大疱性疾病以及硬皮病、银屑病、SLE、妊娠晚期孕妇、健康献血员等）血清样本,并与间接免疫荧光（IIF）试验进行灵敏度和特异度的对比。结果 106份BP患者血清样本中81份BP180抗体诊断试剂盒为阳性,其灵敏度为76.4%;83份抗表皮抗原抗体检测试剂盒（IIF法）为阳性,其灵敏度为78.3%。106份对照组血清标本中95份BP180抗体诊断试剂盒为阴性,其特异度为89.6%;102份抗表皮抗原抗体检测试剂盒为阴性,其特异度为96.2%。BP180抗体诊断试剂盒（ELISA）与对照试剂盒的灵敏度和特异度相比较,差异无统计学意义（P > 0.05）。结论 BP180抗体诊断试剂盒可作为诊断BP的一种辅助手段。     

Autoimmune subepidermal blistering diseases in Uganda: correlation of autoantibody class with age of patients

BACKGROUND: No data are available on the incidence and immunoreactivity of autoimmune subepidermal blistering skin diseases in East Africa. METHODS: All patients with frank blisters/erosions on the skin and/or mucous membranes that attended the Department of Dermatology at Mbarara University, Uganda, from May 2000 to June 2002, were investigated. The diagnosis was based on the clinical presentation and on the presence of circulating autoantibodies detected by indirect immunofluorescence microscopy on 1 m NaCl-split human skin and by Western blotting of recombinant and cell-derived forms of BP180, BP230, and type VII collagen. RESULTS: Twenty-two patients with autoimmune subepidermal blistering skin disorders were identified, including nine with bullous pemphigoid (41%), four with linear immunoglobulin A (IgA) disease (18%), three with mucous membrane pemphigoid (14%), two with linear IgG/IgA bullous dermatosis (9%), and one each with cicatricial pemphigoid and epidermolysis bullosa acquisita (5%). In addition, two patients with immunoreactivity to both the epidermal and dermal side of salt-split skin by indirect immunofluorescence microscopy, who were unreactive to type VII collagen, were provisionally diagnosed as "mixed pemphigoid" (9%). In patients with subepidermal blistering diseases, IgG reactivity correlated significantly with old age, whereas younger patients preferentially developed IgA autoantibodies (P = 0.024). CONCLUSIONS: The age of patients with autoimmune subepidermal blistering diseases appears to influence the immunoglobulin class of autoantibodies. The high frequency of IgA autoantibodies in Ugandan patients may be explained by the age distribution of the Ugandan population.     

盐裂皮肤间接免疫荧光及BP180 NC16a酶联免疫吸附测定在大疱性类天疱疮诊断中的意义

目的 探讨盐裂皮肤间接免疫荧光及大疱性类天疱疮（BP）180 NC16a-酶联免疫吸附测定（ELISA）检测在BP诊断中的意义。方法 收集2015年1月至2017年8月在中国医学科学院皮肤病医院用盐裂皮肤间接免疫荧光（IIF?SSS）和BP180 NC16a?ELISA检测BP患者174例和对照组129例血清。其中25例BP患者用直接免疫荧光（DIF）进行检测并与IIF?SSS和BP180 NC16a?ELISA敏感性进行比较。结果 IIF?SSS、BP180 NC16a?ELISA的敏感性分别为93.67%、96.55%;特异性分别为100%、96.12%。IIF?SSS与BP180 NC16a?ELISA相关系数0.147,为弱相关。其中25例BP患者血清学诊断方法（IIF?SSS,BP180 NC16a?ELISA）和DIF敏感性比较差异无统计学意义。结论 BP血清学诊断方法特异性强、敏感性高,值得临床推广应用。