Subclass distribution of IgG autoantibodies in bullous pemphigoid

The distribution of IgG subclasses in the antibasement membrane zone autoantibody of pemphigoid in skin and serum was analyzed by use of monoclonal antibodies to human IgG subclasses. The predominant subclass was IgG4 which was present in 23 of 24 skin biopsies, IgG1 was next and IgG3 was found only occasionally. In 3 of 24 biopsies IgG4 was the only IgG subclass detected, C3 was absent in 2 of these, the third contained IgM and C3. Serum autoantibodies were similarly analyzed by indirect immunofluorescence (IIF) when again IgG4 autoantibody was the dominant subclass. No IgE autoantibody was detected by IIF.     

辛酸-硫酸胺法对大疱性类天疱疮疱液IgG的纯化

目的:评价辛酸-硫酸胺法纯化的大疱性类天疱疮疱液中IgG的免疫活性。方法:采用辛酸-硫酸胺法分别从正常人血清和大疱性类天疱疮患者疱液中纯化IgG,采用免疫比浊法和SDS-PAGE测定两者提纯后IgG的浓度和纯度,并用ELISA法鉴定疱液提纯前后的免疫活性。结果:辛酸-硫酸胺法从大疱性类天疱疮患者疱液中提纯IgG的回收率为51.4%,略低于正常人血清,提纯前后的免疫活性不变。结论:辛酸-硫酸胺法从大疱性类天疱疮患者疱液中纯化IgG简便可行,纯度高,不影响免疫活性。     

Subclass characteristics of IgG autoantibodies in bullous pemphigoid and pemphigus

Immunoglobulin (Ig) G subclasses in anti-basement membrane zone (BMZ) autoantibodies found in the sera of bullous pemphigoid (BP) and in anti-intercellular substance (ICS) autoantibodies of pemphigus were investigated using immunofluorescent (IF) staining. In BP, IgG4, IgG1, and IgG2 were detected in 13, 5 and 6 of 15 patients, respectively; IgG3 was not detected. In pemphigus, IgG4 was detected in all of 10 patients, IgG1 in 7, IgG2 in one, and IgG3 in one patient, respectively. In both BP and pemphigus, the most prominent subclass in intensity of IF staining was IgG4. Although one BP and one PV patient had only IgG4 autoantibodies, C3 deposition was detected. The quantification of IgG subclasses in the sera of the patients was performed by enzyme-linked immunosorbent assays (ELISA). Serum levels of IgG4 in both BP and pemphigus were elevated approximately 3-fold over those in normal controls; those of whole IgG and IgG1-3 were not significantly elevated. Using direct IF staining, the deposition of C3 at the BMZ and at the ICS was demonstrated in 9 of 10 BP and in 3 of 8 pemphigus patients, respectively. The prominent IgG subclasses of anti-BMZ and anti-ICS antibody were IgG4, a noncomplement-fixing antibody, suggesting that the deposition of C3 in the lesional skin occurred via the alternative pathway, or that small amounts of IgG1-3 subclass autoantibodies activated the classical pathway.     

Autoantibodies to the extracellular and intracellular domain of bullous pemphigoid 180, the putative key autoantigen in bullous pemphigoid, belong predominantly to the IgG1 and IgG4 subclasses

BACKGROUND: Autoantibodies to the extracellular domain (ECD) of bullous pemphigoid (BP) antigen 180 (BP180) are thought to play a crucial part in the pathophysiology of BP. OBJECTIVES: As the various IgG subclasses have different biological properties, we have sought to assess the relative isotype distribution of IgG to BP180 and their reactivity against the ECD and intracellular domain (ICD) of BP180. METHODS: The reactivity of 27 sera from patients with BP was assayed by immunoblotting against recombinant proteins covering the ECD and ICD of BP180. RESULTS: Twenty-seven (100%) and 21 (77%) of 27 BP sera, respectively, contained IgG1 and IgG4 autoantibodies binding to the ECD of BP180. Fourteen (82%) and six (35%) of the 17 BP sera that were reactive with the ICD of BP180 had autoantibodies of the IgG1 and IgG4 subclass, respectively. The profile of the isotype restriction appeared to be similar when the response to the ECD vs. that to the ICD was compared. IgG2 and IgG3 reactivity with BP180 was found less frequently. Patients with BP of longer duration showed a tendency to have, in addition to IgG1, an IgG4 response. CONCLUSIONS: Consistent with prior evidence indicating that subepidermal blister formation in BP is dependent upon complement activation, the frequent finding of complement-fixing IgG1 autoantibodies to both the ECD and ICD of BP180 might have pathogenic relevance in BP. These findings provide new insights relevant for our understanding of the immune response to BP180, the putative key autoantigen in BP.     

A predominant IgG4 subclass may be responsible for false-negative direct immunofluorescence in bullous pemphigoid

BACKGROUND: Bullous pemphigoid (BP) is an immune-mediated blistering disease, usually characterized immunopathologically by the linear deposition of IgG and C3 along the basement membrane zone (BMZ) of skin. However, positive deposition of C3 but negative staining for IgG on direct immunofluorescence (DIF) studies has been noted in some patients. METHODS: Twelve patients known to have BP but with absence of staining for IgG were included in this study. Frozen sections of skin specimens from the 12 patients were subjected to IgG DIF, as well as a sandwich double antibody method of staining for IgG, IgG subclasses, and light chains. Enzyme-linked immunosorbent assay (ELISA) using commercially available human IgG subclasses was used to analyze the subclass restriction of FITC-labeled antihuman IgG conjugates. RESULTS: Of the 12 skin specimens with positive C3 and negative IgG on DIF, nine were positive for IgG with the double antibody sandwich method. In addition, all 12 specimens had positive linear staining for the subclass IgG4 along the BMZ with this method. There was no IgG light chain restriction. Two commercially obtained antihuman IgG conjugates, both commonly used in our laboratory for DIF testing, were analyzed for separate IgG subclass specificity by ELISA. Both conjugates showed high reactivity to IgG1 and IgG3 with less reactivity to IgG2 and IgG4. CONCLUSION: These results suggest that the following factors contribute to false-negative staining for IgG on DIF in some BP patients: (i): subthreshold IgG in skin specimens; (ii) limited reactivity of commercial antihuman IgG conjugates to the IgG4 subclass; and (iii) decreased sensitivity of DIF compared with double antibody methods for the detection of IgG. The use of sandwich double antibody immunofluorescence methods to test for IgG and/or IgG subclasses may be helpful in definitively diagnosing BP in patients with negative IgG and positive C3 staining on DIF.     

Cicatricial pemphigoid with circulating autoantibodies to beta4 integrin, bullous pemphigoid 180 and bullous pemphigoid 230

Cicatricial pemphigoid is a heterogeneous group of autoimmune subepidermal blistering diseases associated most commonly with autoantibodies to bullous pemphigoid (BP)180 and less frequently with those to laminin 5 or type VII collagen. In addition, a few cases have been described with autoantibodies to the beta4 subunit of alpha6beta4 integrin. We describe a patient with extensive disease of ocular, oral, pharyngeal, laryngeal and genital mucous membranes that healed with scarring of conjunctivae. IgG autoantibodies bound to the dermal-epidermal junction on direct immunofluorescence (IF) microscopy and to the epidermal side of 1 mol L(-1) NaCl-split skin on indirect IF microscopy. Our patient's circulating IgG recognized a 205-kDa protein in extracts of 293T cells transfected with the beta4 subunit of alpha6beta4 integrin and in the cell extract of DJM-1 cells. Our patient's IgG and IgA autoantibodies also reacted with full-length BP180 derived from epidermal extracts and the ectodomain of BP180 (LAD-1) derived from culture supernatant of keratinocytes. In addition, a weak IgG reaction with BP230 was noted. The disease rapidly responded to dexamethasone-cyclophosphamide pulse therapy, and immunoblot reactivity to both beta4 integrin and BP180 decreased according to disease activity.     

The distribution of IgG subclass autoantibodies in bullous pemphigoid analysed by immunofluorescence and immunoblotting

Summary The distribution of IgG subclasses in bullous pemphigoid (BP) autoantibodies in 14 BP sera and four biopsies was analysed by immunofluorescence (IF) and immunoblotting (IB). Three clones of monoclonal antibodies (MoAbs) to each IgG subclass were used. All 14 sera showed linear fluorescence in the basement membrane zone with IF, and 240 kDa and/or 180 kDa protein bands in human epidermal extract were detected by IB using a polyclonal antibody to total IgG. BP antibody in IgG₄ subclass was found to be predominant, as it was detected most frequently and intensively in all positive sera and lesions studied by both techniques. In the IgG₁ to IgG₃ subclasses, a range of proportions of positive sera was obtained among MoAbs to the same IgG subclass in both techniques. However, one MoAb could detect IgG₁ subclass BP antibody with a high frequency in both techniques. No difference in IgG subclass distribution of BP antibodies was observed during the course of the disease. In each serum, any IgG subclass of BP antibody recognized the identical BP antigen(s). These results suggest the predominance of IgG₄ subclass and the possible presence of IgG₁ subclass in BP antibodies.     

Erythrodermic bullous pemphigoid is a clinical variant of bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease of the skin. Several variants olBP have been described but until recently the relationship of these variants to generalized BP was unclear. Several studies have shown that pemphigoid nodularis, pemphigoid vegetans, localized BP and vesicular pemphigoid are true variants of BP as the circulating antibodies in these patients recognize the same 230kDa BP antigen as found in patients with generalized BP. Erythrodermic BP is a very unusual variant characterized by an erythroderma along with blister formation. We describe the third known patient to develop erythrodermic BP and characterize the antigenic specificity of the circulating antibodies in both our newly reported patient with erythrodermic BP and in one of the two other previously reported cases of erythrodermic BP. Both patients with erythrodermic BP had circulating IgG antibodies which bound to the epidermal side of salt-split human skin in a pattern identical to two patients with immunopathologically proven generalized BP. Sera from four erythrodermic patients without blisters and from a healthy normal volunteer, as controls, failed to demonstrate detectable circulating IgG autoantibodies. Immunoprecipitation studies revealed that both patients with erythrodermic BP had circulating IgG autoantibodies which recognized, to varying degrees, the same 230 and 180kDa BP antigens as recognized by sera from two patients with immunopathologically proven generalized BP. Sera from four erythrodermic patients without blisters and from a healthy normal volunteer, as controls, failed to recognize any specific polypeptides. These observations demonstrate that erythrodermic BP is a distinct clinical variant of BP.     

大疱性类天疱疮抗原1和2在大疱性类天疱疮并发神经系统损害中的作用

大疱性类天疱疮可见于多种神经系统疾病患者,二者并发的机制尚不清楚.动物研究证实鼠大疱性类天疱疮抗原(BPAG)1至少存在3种亚型:皮肤亚型、神经业型和肌肉亚型.BPAG2除在皮肤有表达外,在人脑神经元也有广泛表达.有可能神经系统病变导致BPAG1和BPAG2神经亚型暴露于免疫系统,产生拮抗神经亚型的抗体,与皮肤亚型发生免疫反应及交叉反应,导致大疱性类天疱疮发生.     

药物诱发大疱性类天疱疮的研究进展

【摘要】 药物诱发大疱性类天疱疮（BP）是指由系统或局部用药后诱发的一种特殊类型BP。对所有新发或是突然加重的BP患者，应警惕药物诱发的可能性，特别是近年报道较多的疫苗接种及二肽基肽酶4抑制剂、肿瘤坏死因子α拮抗剂和程序性死亡受体1/程序性死亡配体1抑制剂等新型药物。本文综述近年来药物诱发BP的研究进展。     

Trauma-induced bullous pemphigoid

We describe three patients with bullous pemphigoid who presented with bullae at sites of trauma and with little spread of the condition outside such areas. The diagnosis was confirmed by histology and direct and/or indirect immunofluorescence; electron microscopy was performed in two cases to rule out the diagnosis of epidermolysis bullosa acquisita (EBA). Treatment was with either systemic steroids or ACTH in all three cases. Trauma-induced bullous pemphigoid should be included in the differential diagnosis of localized blistering eruptions.     

Erythrodermic bullous pemphigoid

We report a case of erythrodermic type of bullous pemphigoid which is a rare variant of bullous pemphigoid. Our patient had a peculiar clinical presentation with bullae, erosions and extensive erythrodermic areas, and distinct direct immunofluorescent findings which included linear IgG and C3 deposits in the basement membrane and also IgG in the intercellular spaces. Very high levels of serum IgE were also detected in our patient.     

儿童大疱性类天疱疮的研究进展

大疱性类天疱疮（BP）是一种常见的表皮下自身免疫性水疱病,临床表现为正常皮肤或者红斑基础上出现疱壁紧张的水疱、大疱,可以继发糜烂、渗出、感染和结痂,黏膜受累相对少见。免疫荧光检查可见真表皮交界处有IgG和（或）C3沉积,血液中可以检测到抗BP180或BP230的抗体。BP主要发病人群为 > 60岁的老年人,偶尔发生于儿童,包括婴儿。儿童BP与成人BP相比,既具有共同的临床表现,又有区别,预后也不尽相同……