The use of chemically split tissue in the detection of circulating anti-basement membrane zone antibodies in bullous pemphigoid and cicatricial pemphigoid

Human skin and mucous membranes were used to detect circulating auto-antibodies by indirect immunofluorescence in 20 patients with bullous pemphigoid and eight with cicatricial pemphigoid. The tissue substrate was used intact and after chemical separation through the basement membrane zone (BMZ) by incubation with I M NaCl. Chemically split skin and oral mucosa provided a more sensitive assay for demonstrating circulating anti BMZ antibodies. Use of a battery of substrates increased the number of positives in bullous pemphigoid from 30% detected on monkey oesophagus to 100% (tissue battery). In cicatricial pemphigoid there was an increase in the proportion of positive sera from 13% (monkey oesophagus) to 88% (tissue battery). In addition, a different class of antibody was frequently detected on split tissue substrate suggesting that new antigens are exposed by this procedure.     

Serological diagnosis of bullous pemphigoid (BP): comparison of the sensitivity of indirect immunofluorescence on salt-split to immunoblotting

Specialized immunological assays are required for the accurate diagnosis of bullous dermatoses such as bullous pemphigoid (BP), epidermolysis bullosa acquisita and bullous lupus erythematosus. The aim of this study was to analyse and compare the sensitivity of indirect immunofluorescence (IF) on salt-split skin and immunoblotting for the detection of circulating autoantibodies in BP. Of the BP patients selected for the study, 74/79 (94%) had circulating autoantibodies detected by at least one of the two methods. Both methods had comparable sensitivity and detected BP-specific autoantibodies in 82-85% of the patients. Because 20% of the patients were found to be positive by only one of the methods, both methods should be used in the diagnosis of BP. Indirect IF on salt-split skin is easier to perform and is preferable in routine analysis, but Western blotting may be used as a complementary assay with sera showing no reactivity on salt-split skin.     

Bullous pemphigoid in Liguria: A 2-year survey

BACKGROUND: The epidemiology of bullous pemphigoid (BP) is not clear because of the heterogeneity of the disease, and its possible association with internal malignancies has been under debate for many years. We report the findings of a 2-year study on incident BP cases in the Liguria region of Italy. SUBJECTS AND METHODS: Thirty-two patients with BP were collected over the 2-year period. Diagnosis was made based on clinical findings and confirmed by histology, direct immunofluorescence (DIF) and indirect immunofluorescence (IIF) with salt-split skin and monkey oesophagus, and immunoblotting (IB). All patients were thoroughly investigated for possible malignancies and all were followed up for 6 months to monitor the response to treatment. RESULTS: DIF showed linear deposits at the dermoepidermal junction in all but one patient. IIF gave positive findings for 15 sera tested with monkey oesophagus and 20 tested with salt-split skin. IB gave positive findings in 19 cases. There was a malignancy in six cases, but no clinical or immunological features that could be considered to predict this occurrence. CONCLUSIONS: The findings of this study are in accordance with most of the data found in the literature, including the fact that IgG serum levels did not predict the course of the disease. Contrary to previous indications, IgE levels were not indicative of disease course either. Mucosal lesions, erythema multiform-like lesions, negative IIF findings and antibodies to AgPB2 were not a prediction for the development of malignancy.     

Antidesmoplakin antibodies in pemphigus vulgaris

Background Besides being present in paraneoplastic pemphigus (PNP), circulating antidesmoplakin (DP) antibodies have been found anecdotally in other bullous diseases, including pemphigus foliaceus and pemphigus vulgaris. Objectives To verify how frequent anti‐DP antibodies are in pemphigus vulgaris. Methods We studied 48 sera from patients with proven pemphigus vulgaris (29 mucosal dominant pemphigus and 19 mucocutaneous pemphigus) by indirect immunofluorescence (IIF) with rat bladder epithelium (RBE) as a substrate and by immunoblotting (IB) on human keratinocyte cultures enriched in DP. Results Ten sera (21%) were positive in IIF on RBE. By IB, eight sera proved to have antibodies to both DP I (250 kDa) and DP II (210 kDa), one serum had antibodies directed to DP I only, and two sera to DP II only. Conclusions Our data confirm that RBE is not a specific IIF substrate for the serological diagnosis of PNP. It remains a sensitive and specific substrate for the detection of anti‐DP antibodies, which, in patients with pemphigus vulgaris, are probably caused by an epitope‐spreading phenomenon.     

Drug-induced bullous pemphigoid with dermal fluorescence on salt-split skin

The immunological features of drug-induced bullous pemphigoid appear to be similar to those of idiopathic bullous pemphigoid (BP), with presence of circulating and tissue-bound antibodies showing anti-basement membrane zone specificity. We describe a 28-year-old woman who developed a widespread blistering eruption with marked involvement of the mucous membranes shortly after commencing treatment with oral flucloxacillin. The eruption gradually cleared following drug withdrawal and treatment with oral corticosteroids. Indirect immunofluorescence showed circulating IgG anti-basement membrane zone (BMZ) antibody and C3 which bound to the dermal aspect of salt-split skin, and direct immunofluorescence (IMF) of perilesional skin showed a linear band of C3 at the BMZ. Western immunoblotting of the patient's serum showed positive reactivity with a 180 kDa antigen in epidermal extracts and no reactivity with dermal extracts. The dermal-binding pattern on indirect IMF with salt-split skin only occurs in a minority of patients with BP and has not been described previously in a drug-induced case.     

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.     

大疱性系统性红斑狼疮的皮肤基底膜带相关抗原

免疫印迹和盐裂皮肤间接免疫荧光检测 ５例大疱性系统红斑狼疮（ＢＳＬＥ）血清，对照为 ５例获得性大疤性表皮松解症（ＥＢＡ）、２０例类天疱疮（ＢＰ）、２０例ＳＬＥ和１０例正常人血清。结果表明，３例（３／５）ＢＳＬＥ血清结合盐裂皮肤真皮侧和真皮提取物中２９０ ０００抗原，其中２例ＢＳＬＥ血清也结合表皮提取物中 １６５ ０００抗原，结果与 ＥＢＡ和部分ＢＰ血清相同。ＳＬＥ血清未结合 ２９０ ０００和 １６５ ０００抗原。提示ＢＳＬＥ血清中存在ＥＢＡ和ＢＰ抗体，推测ＥＢＡ和ＢＰ抗原可能是ＢＳＬＥ的皮肤基底膜带相关抗原。     

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.     

Bullous pemphigoid antibodies. Human skin as a substrate for indirect immunofluorescence assay

Human skin, the target organ for bullous pemphigoid (BP) antibodies, is thought to be a less sensitive substrate for the indirect immunofluorescence assay of BP antibodies than monkey or guinea pig esophagus. To examine the reasons for this puzzling phenomenon, we compared the titers of BP antibodies obtained when human skin, monkey, and guinea pig esophagus were used as substrates. We found the titers of BP antibodies obtained with human skin from sites commonly involved in BP (flexor arm, flexor thigh, popliteal fossa) were as high and usually higher than those obtained with monkey and guinea pig esophagus. In contrast, much lower titers were obtained with human skin from sites rarely involved in the disease (scalp, face, extensor arm). These findings suggest that human skin as a substrate is at least as sensitive as monkey or guinea pig esophagus for the indirect immunofluorescence assay of BP antibodies when the skin is obtained from regions on the body commonly involved in BP.     

Evaluation of salt split technique of immunofluorescence in bullous pemphigoid

Recent studies suggest that salt split skin is a more sensitive substrate than intact skin for immunofluorescence diagnosis of bullous pemphigoid. We undertook this study to define the role of salt split technique of immunofluorescence findings in 32 clinical and histopathology confirmed cases of bullous pemphigoid. Both direct and indirect immunofluorescences were performed using normal and split skin. Direct immunofluorescence positivity of 100% was noted with both routine and salt split method. Additional immunoreactant deposition was noted with direct method on split skin in 5 cases. Patterns of fluorescence in the latter were roof (40.60%), floor (9.4%) and combined roof and floor (50%). On indirect immunofluorescence, positivity was almost doubled with salt split technique ( 68%) as compared to routine method (36%). Thus, salt split technique was equivalent to routine on direct method in positivity with additional immunoreactant deposits noted in some and had double the sensitivity of the indirect method in detecting immunofluorescence in bullous pemphigoid.     

Studies of cicatricial pemphigoid autoantibodies using direct immunoelectron microscopy and immunoblot analysis

We studied 11 consecutive patients with classical cicatricial pemphigoid (CP) using direct immunoelectron microscopy (IEM) and Western immunoblotting analysis. Direct IEM performed in the skin or gingival mucosa revealed in all 11 CP patients that immunoglobulins and complement deposits were usually thick and discontinuous along the dermoepidermal junction, mostly localized on the lamina densa and occasionally in the lamina lucida. By direct IEM, the ultrastructural aspect in CP differs from the pattern observed in bullous pemphigoid (BP) and from that of chronic epidermolysis bullosa acquisita (EBA). Nine CP patients were studied by Western immunoblotting and, of these nine, only two had detectable anti-basement membrane zone (BMZ) antibodies by indirect immunofluorescence on salt-split skin. By immunoblotting performed on protein extracts of heat-separated epidermis, eight out of the nine CP sera specifically reacted with two protein bands of approximately 230-240 kD and 180 kD, similar to those recognized by BP sera in co-migration experiments. By immunoblotting on skin BMZ extracts, none of these nine CP sera recognized the 290-kD major polypeptide of EBA antigen. Taken together, these results suggest that, in CP, the target-antigen, as identified on immunoblots, is similar to BP antigen, but with an abnormal expression within the dermoepidermal junction of patients, which may in part explain the scarring course of the disease.     

Calcium enhances the sensitivity of immunofluorescence for pemphigus antibodies

Indirect immunofluorescence (IF) to detect pemphigus and pemphigoid autoantibodies is commonly performed with monkey esophagus (ME) as substrate and phosphate-buffered saline (PBS) as a diluent. The purpose of this study was to evaluate comparative IF titers using human skin (HS) as substrate with variations in the buffers employed. Substrates (ME or HS) were incubated in PBS, Tris-acetate-buffered saline (TAS), TAS with 5 mM CaCl+2 (TAS-Ca+2), and PBS or TAS with 1 mM EDTA, prior to incubation with pemphigus or pemphigoid sera for indirect IF. We examined sera from 11 patients with pemphigus vulgaris (PV), 10 patients with Brazilian pemphigus foliaceus (BPF), and 4 patients with bullous pemphigoid. In 20 of 21 pemphigus sera, endpoint indirect IF titers were highest on normal skin with TAS-Ca+2. Six sera (2 PV and 4 BPF) had endpoints that were 5 double dilutions higher than the endpoints obtained with ME and PBS. Six sera (3 PV and 3 BPF) were 4 double dilutions higher, 7 sera (3 PV and 4 BPF) were 2-3 double dilutions higher, and 2 PV sera were equivalent with both substrate/buffers. Preincubation of either tissue with EDTA prior to indirect IF abolished PV and BPF antibody binding completely. Exposure to EDTA after the tissue was incubated with PV or BPF sera did not affect indirect IF titers. In the presence of Ca+2, the antigen was resistant to trypsin in concentrations of 0.001%; however, in the absence of added Ca+2 it was destroyed by 0.0001% trypsin. These differences were not observed with bullous pemphigoid sera; all 4 sera had similar endpoint indirect IF titers. This study shows a significant increase in the sensitivity of indirect IF assays for pemphigus autoantibodies by the use of Ca+2-supplemented buffers on human skin. This finding may also have implications for procedures designed to purify and/or detect pemphigus antigens.     

DIFFERENTIATION OF BULLOUS PEMPHIGOID FROM EPIDERMOLYSIS BULLOSA ACQUISITA ON FROZEN SKIN BIOPSIES

Patients with bullous pemphigoid and epidermolysis bullosa acquisita may have similar clinical, histologic, and routine immunohistologic features. These two diseases can be distinguished by routine diagnostic studies either on a patient's serum tested by indirect immunofluorescence on salt-split normal skin or by obtaining a fresh perilesional skin biopsy, inducing a split at the lamina lucida, and testing for the site of IgG deposition by direct immunofluorescence. Often the serum studies are negative, while direct immunofluorescent studies yield the characteristic linear IgG staining of the basement membrane zone. To eliminate the need for a repeat biopsy to make a laboratory differential diagnosis, we studied the efficacy of salt-splitting perilesional skin biopsies that had been previously submitted and frozen for routine direct immunofluorescent studies. The biopsies were thawed, salt-split, and processed for direct immunofluorescence. Three epidermolysis bullosa acquisita biopsies and seven bullous pemphigoid biopsies examined demonstrated IgG staining at sites consistent with their respective diagnoses. The IgG appeared in the dermal side of the split biopsies in epidermolysis bullosa acquisita and predominantly, or exclusively, in the epidermal side in bullous pemphigoid. Thus the direct immunofluorescent study of previously frozen and subsequently salt-split skin biopsies may be used for the differential diagnosis of bullous pemphigoid from epidermolysis bullosa acquisita. In most cases, it may eliminate the need for a repeat biopsy.     

Anti-p200 pemphigoid responding to dapsone

Anti-p200 pemphigoid is a rare autoimmune subepidermal blistering disease. Clinical presentation is similar to standard bullous pemphigoid (BP) but mucous membranes and cephalic lesions are more frequent. Histology and direct immunofluorescence (IF) are identical to BP but indirect IF discloses linear deposits of immunoglobulin G (IgG) on the dermal side of artificial salt-split skin. Specific diagnosis is based on western immunoblotting that shows circulating IgG recognizing a 200-kDa protein localized on the dermal extract. The 200-kDa antigen was recently identified as laminin γ1. Anti-p200 pemphigoid should be considered before all atypical or topical steroid-resistant bullous disease, as well as mucous membranes pemphigoid or epidermolysis bullosa acquisita. Dapsone appears to be the most effective treatment and should be used as the first option in combination with topical steroids. In this report, we describe the case of a patient with a typical clinical and immunopathological anti-p200 pemphigoid, responding to a combination of topical steroids and dapsone.     

Frequency of IgA antibodies in pemphigus, bullous pemphigoid and mucous membrane pemphigoid

Circulating and bound IgA antibodies can be found in the autoimmune blistering diseases, but their prevalence, clinical relevance and target antigens remain unknown. Thirty-two patients with pemphigus, 73 with bullous pemphigoid and 28 with mucous membrane pemphigoid were studied retrospectively. Direct immunofluorescence (DIF) analysis of IgG, IgA, IgM and C3 was carried out for all cases. Sera were studied by standard indirect immunofluorescence, indirect immunofluorescence on salt-split skin, immunoblotting for bullous pemphigoid and mucous membrane pemphigoid and ELISA for pemphigus. With DIF, we found IgA autoantibodies in 22 of all 133 cases. Circulating IgA antibodies to skin were detected in 2 of 3 IgA-DIF-positive patients with pemphigus, in 3 of 6 with bullous pemphigoid, and in 6 of 13 with mucous membrane pemphigoid. We confirm that the IgA reactivity is more frequently associated with mucous membrane involvement, especially in cases without critical involvement (5/8). The role of IgA and its antigenic specificity in these diseases remain unclear.     

Immunohistochemical study on 70 human embryos concerning the epidermal binding of pemphigus and pemphigoid antibodies

In the present study, the development of pemphigus and bullous pemphigoid antigens was investigated by means of the indirect immunofluorescence technique using sera of pemphigus and bullous pemphigoid patients, respectively, on human foetus skin antigenic substrate. Seventy skin specimens from embryos of 9-38 weeks of gestation were studied. Both pemphigus and bullous pemphigoid antigens were observed for the first time at about 16 weeks of gestation. Pemphigus antigen has a slower rate of evolution. Between 30 and 38 weeks both antigens were detected as strongly positive.     

Characterization of the antibody response in oesophageal cicatricial pemphigoid

Cicatricial pemphigoid (CP) is a subepidermal, autoimmune bullous dermatosis. It is classified as a clinical subset of bullous pemphigoid (BP). However, it differs from BP in some significant ways: (i) in CP mucosal involvement with clinical scarring is prominent; (ii) there is a prominent IgA class antibody response alone or in addition to the IgG class antibody response; and (iii) there is a heterogeneous antibody response in CP, whereas in BP the majority of the antibodies are directed against a 180-kDa hemidesmosomal protein, bullous pemphigoid antigen 2 (BPAg2). Oesophageal involvement in CP is a rare, but often devastating manifestation. In this study we examined the humoral autoimmune response in oesophageal CP, in an attempt to characterize the autoantibody reactivity profile. We used direct and indirect immunofluorescence and Western immunoblotting using normal human skin and oesophagus substrates. We studied patient sera over time in order to search for evidence of epitope spreading in these patients. All patients had positive direct immunofluorescence of perilesional oesophageal epithelium. All patients had positive circulating antibasement membrane zone autoantibody titres. There was a significant IgA class in addition to an IgG class autoantibody response. IgA and IgG antibodies demonstrated significant reactivity with BPAg2 and the 97 kDa linear IgA disease antigen on Western immunoblot suggesting intraprotein epitope spreading. There was no evidence of interprotein epitope spreading over time. Our findings suggest that there is a heterogeneous antibody response in oesophageal CP with the predominant antigen being BPAg2.     

Linear IgA Bullous Dermatosis of Childhood with Autoantibodies to a 230 kDa Epidermal Antigen

Abstract: Linear IgA bullous dermatosis (LABD) is an autoimmune, subepidermal disease defined on the basis of direct immunofluorescence findings. However, more recent techniques used to study bullous dermatoses suggest that LABD may be heterogeneous. A patient with LABD of childhood (chronic benign disease of childhood, CBDC) was studied by indirect immunofluorescence on salt-split skin and by Western blot in an attempt to characterize the involved autoantigen. This young girl's periorificial (mouth, genitalia), erythematovesicular lesions were diagnosed initially as herpes simplex. Histologic examination revealed eosinophilic spongiosis, suggesting the diagnosis of an autoimmune blistering disease. Direct immunofluorescence showed an exclusive linear IgA deposit at the dermoepidermal junction. Indirect immunofluorescence revealed circulating IgA autoantibodies that reacted with the epidermal side of saltsplit skin; these reacted by Western blot with a 230 kDa epidermal antigen, as in bullous pemphigoid. This case, fulfilling the diagnostic clinical and direct immunofluorescence criteria for LABD/CBDC, seems to represent IgA bullous pemphigoid. It further underscores the nosologic heterogeneity of LABD, which probably includes, apart from bullous pemphigoid, epidermolysis bullosa acquisita and cicatricial pemphigoid.     

Antigen specificities of antibasement membrane zone antibodies: immunofluorescence and Western immunoblotting studies

Summary To clarify the antigen specificities of autoantibodies in sera and blister fluids from patients diagnosed as bullous pemphigoid (BP) by routine histology and immunofluorescence (IF) methods, indirect IF studies using the salt split-skin technique were performed. In addition, to detect the BP antigen(s) in human epidermal extracts, Western immunoblotting analyses were carried out. Of 41 sera, 39 (95%) showed a linear pattern of fluorescence along the epidermal side of the separation. Two (5%) sera showed a linear pattern of fluorescence along the dermal side. Blister fluids produced IF staining patterns identical with those of serum samples. These fluorescence patterns were not related to the BP antigen expression of the skin used as substrates. In Western immunoblotting analyses, selected sera showing an epidermal pattern on separated skin primarily reacted with 240 kD, 220 kD, 180 kD, and 150 kD proteins extracted from normal human epidermis. Two sera showing a dermal pattern on separated skin revealed no specific bands. The protein bands recognized by blister fluids were indentical with those of serum samples. These results indicated that blister fluids are also available in immunological analysis, and that BP antibodies have more than one antigenic specificity. Moreover, it is suggested that differential diagnosis between BP and other bullous diseases may be more important than previously recognized, particularly in patients with epidermolysis bullosa acquisita (EBA).     

U-serrated immunodeposition pattern differentiates type VII collagen targeting bullous diseases from other subepidermal bullous autoimmune diseases

BACKGROUND: Epidermolysis bullosa acquisita (EBA) can be differentiated from other subepidermal bullous diseases by sophisticated techniques such as immunoelectron microscopy, salt-split skin antigen mapping, fluorescence overlay antigen mapping, immunoblot and enzyme-linked immunosorbent assay. OBJECTIVES: To determine whether the diagnosis can also be made by routine direct immunofluorescence microscopy. METHODS: We studied frozen skin biopsies from 157 patients with various subepidermal immunobullous diseases. RESULTS: We found three distinct 'linear' fluorescence patterns at the basement membrane zone: true linear, n-serrated and u-serrated. The true linear pattern, often seen in conjunction with either the n- or the u-serrated pattern, was found in any subepidermal immunobullous disease with nongranular depositions. In bullous pemphigoid, mucous membrane pemphigoid, antiepiligrin cicatricial pemphigoid, p200 pemphigoid and linear IgA disease the n-serrated pattern was found, corresponding with depositions located in hemidesmosomes, lamina lucida or lamina densa. However, in EBA and bullous systemic lupus erythematosus the u-serrated staining pattern was seen, corresponding with the ultralocalization of type VII collagen in the sublamina densa zone. The diagnosis of EBA with IgG or IgA autoantibodies directed against type VII collagen was confirmed by immunoelectron microscopy, salt-split skin antigen mapping, fluorescence overlay antigen mapping or immunoblotting. CONCLUSIONS: Using this pattern recognition by direct immunofluorescence microscopy we discovered several cases of EBA which would otherwise have been erroneously diagnosed as a form of pemphigoid or linear IgA disease.