Immunofluorescence serration pattern analysis as a diagnostic criterion in antilaminin-332 mucous membrane pemphigoid: immunopathological findings and clinical experience in 10 Dutch patients

Background Antilaminin‐332 mucous membrane pemphigoid (anti‐LN‐332 MMP) is a chronic subepidermal blistering disease characterized by IgG anti‐epidermal basement membrane zone (BMZ) autoantibodies against laminin‐332 (LN‐332). Patients with anti‐LN‐332 MMP have an increased relative risk of malignancy. Laboratory techniques that are difficult to obtain are needed for diagnosis of anti‐LN‐332 MMP. Objectives To incorporate direct immunofluorescence (DIF) serration pattern analysis of IgG depositions in the diagnostic criteria of anti‐LN‐332 MMP. Methods Patients who met our revised inclusion criteria for anti‐LN‐332 MMP were selected from our biobank over the period 1997–2009. Inclusion criteria were clinical symptoms, DIF serration pattern analysis, indirect immunofluorescence (IIF) on salt‐split skin, and antigen‐specificity analysis of the serum including immunoblotting and/or immunoprecipitation and/or enzyme‐linked immunosorbent assay (ELISA) against native LN‐332. Results Ten patients met the inclusion criteria. A malignancy was found in two patients (20%). In all patients in whom it was performed (n = 9), DIF showed linear IgG deposition along the BMZ in an n‐serrated pattern. Nine sera reacted by salt‐split skin analysis and bound to the dermal side of the split skin. ELISA against native LN‐332 was positive in 78% of the tested sera. Conclusions Anti‐LN‐332 MMP can clinically resemble other forms of pemphigoid. Although state‐of‐the‐art laboratory diagnostics are necessary for definite diagnosis, the combination of simple DIF serration pattern and IIF salt‐split skin analysis will exclude other forms of MMP and epidermolysis bullosa acquisita from the differential diagnosis. Because of the increased risk for malignancy patients should be thoroughly oncologically screened.     

Mucous membrane pemphigoid with generalized blisters: IgA and IgG autoantibodies target both laminin-332 and type XVII collagen

Mucous membrane pemphigoid (MMP) is a mucous membrane-dominated, subepidermal autoimmune blistering disease in which autoantibodies usually react with the C-terminal domain of type XVII collagen (COL17) or with laminin-332. Only a few cases of MMP with widespread blisters have been reported. Serologically, IgA and IgG class autoantibodies directed against COL17 or IgG autoantibodies directed against laminin-332 in patients with MMP have been well documented. MMP cases in which IgA reacts with laminin-332, however, are extremely rare. We report a case of MMP in a 67-year-old man. Clinical examination revealed extensive mucosal lesions as well as generalized blisters and erosions that healed with scar formation. The disease was intractable to treatment with systemic steroids. Interestingly, in addition to IgG directed against laminin-332 and the noncollagenous 16A (NC16A) and C-terminal domains of COL17, circulating IgA reacting with laminin-332 and with the NC16A domain of COL17 was also detected. This is the first MMP case with circulating IgA and IgG autoantibodies against both laminin-332 and COL17.     

IgG, IgA and IgE autoantibodies against the ectodomain of BP180 in patients with bullous and cicatricial pemphigoid and linear IgA bullous dermatosis

BACKGROUND: Bullous pemphigoid (BP), linear IgA bullous dermatosis (LABD) and cicatricial pemphigoid (CP) are clinically distinct autoimmune bullous skin diseases characterized by autoantibodies against components of the epidermal basement membrane. Like most patients with BP, a significant subgroup of patients with CP has circulating IgG specific for BP180, a transmembraneous protein of hemidesmosomes. Moreover, sera of patients with LABD contain IgA autoantibodies reactive with a 97/120-kDa protein, LABD antigen 1, which is highly homologous to the extracellular portion of BP180. OBJECTIVES: We aimed to determine whether, in these diseases, autoantibody reactivity to BP180 is restricted to distinct immunoglobulin subtypes. METHODS: Utilizing a baculovirus-encoded form of the ectodomain of BP180, sera from patients with BP (n = 10), CP (n = 9), LABD (n = 10) and normal human control sera (n = 10) were analysed by immunoblot for IgG, IgA and IgE reactivity against BP180. RESULTS: All of 10 BP sera displayed IgG, IgA and IgE reactivity with BP180. Six and seven of nine CP sera, respectively, contained IgG and IgA autoantibodies reactive with BP180, but none of nine sera contained BP180-specific IgE. Nine of 10 LABD sera contained IgA, and six of 10 IgG, which was reactive with BP180, but none of 10 sera showed IgE reactivity to BP180. CONCLUSIONS: The presence of IgG and IgA autoantibody responses to BP180 in patients with three clinically distinct autoimmune bullous diseases indicates that an autoimmune response to the same distinct adhesion protein may lead to different clinical manifestations. It is therefore conceivable that variable epitopes of BP180 are targeted by the different autoantibody isotypes, resulting in the distinct clinical pictures.     

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.     

Case of epidermolysis bullosa acquisita with concomitant anti‐laminin‐332 antibodies

Subepidermal autoimmune blistering disease including bullous pemphigoid, pemphigoid gestationis, mucous membrane pemphigoid, anti‐laminin‐γ1 pemphigoid, linear immunoglobulin A bullous disease and epidermolysis bullosa acquisita (EBA), are all characterized by direct immunofluorescence microscopy or immunoglobulin deposition on the basement membrane zone. Among them, EBA is a rare acquired subepidermal autoimmune blistering disease of the skin and mucous membranes reactive with type VII collagen, a major component of the epidermal basement membrane zone. Anti‐laminin‐332‐type mucous membrane pemphigoid has pathogenic autoantibodies against laminin‐332, which is a basement membrane heterotrimeric protein composed of α3, β3 and γ2 laminin chains. We describe a 73‐year‐old Japanese man presenting with multiple, annular, tense blisters on the lower legs and oral lesions. Despite the severe clinical manifestations, the disease was successfully controlled by combination therapy of oral prednisolone and mizoribine. This case was confirmed to have autoantibodies to both type VII collagen and laminin‐332 α3 chain by indirect immunofluorescence of 1 mol NaCl‐split normal human skin, various immunoblot analyses and enzyme‐linked immunosorbent assays. This case was a rare case of EBA with concomitant anti‐laminin‐332 antibodies.     

Development of a simple enzyme‐linked immunosorbent assay for the detection of autoantibodies in anti‐p200 pemphigoid

Background Anti‐p200 pemphigoid is a subepidermal blistering skin disease characterized by autoantibodies against a 200‐kDa protein (p200) of the dermal–epidermal junction. The laminin γ1 chain has recently been identified as target antigen in this disease and the C‐terminus was described as an immunodominant region of laminin γ1. Diagnosis of anti‐p200 pemphigoid requires detection of serum IgG at the dermal side of 1 mol L^?1 salt‐split skin by indirect immunofluorescence microscopy and labelling of a 200‐kDa protein by Western blotting of dermal extract. However, preparation of dermal extract is not widely available, limiting the possibility of diagnosing this disease to a few laboratories. Objectives To develop a simple, sensitive and specific diagnostic tool for anti‐p200 pemphigoid. Methods Sera from patients with anti‐p200 pemphigoid (n = 35), bullous pemphigoid (BP, n = 101), epidermolysis bullosa acquisita (EBA, n = 10), antilaminin 332 mucous membrane pemphigoid (MMP, n = 14), pemphigus vulgaris (PV, n = 51) and healthy volunteers (HV, n = 131) were tested by a novel enzyme‐linked immunosorbent assay (ELISA) that employed a recombinant monomeric C‐terminal fragment of human laminin γ1 (hLAMC1‐cterm) expressed in Escherichia coli. Results Serum reactivity with hLAMC1‐cterm was detected in sera from 24 of 35 (69%) patients with anti‐p200 pemphigoid, two of 101 (2%) with BP, 0 of 10 with EBA, two of 14 (14%) with anti‐laminin 332 MMP, 0 of 51 with PV, and 0 of 131 HV. Conclusions This novel ELISA will facilitate the diagnosis of anti‐p200 pemphigoid.     

Anti‐Laminin‐332 Mucous Membrane Pemphigoid in a 9‐Year Old Girl

Mucous membrane pemphigoid (MMP), an autoimmune subepithelial blistering disease that predominantly affects the mucous membranes, is usually diagnosed in elderly adults. Early diagnosis of MMP is crucial because it tends to run a chronic and progressive course with the potential for devastating scarring of the mucous membranes that may lead to blindness and airway compromise. A subtype of MMP, anti‐laminin‐332 MMP, is a rare blistering disorder in which autoantibodies are directed against laminin‐332 (formerly epiligrin), a structural protein of the epidermal basement membrane. Herein we report what we believe to be the youngest patient diagnosed with anti‐laminin‐332 MMP, a 9‐year‐old girl with disease affecting only the oral, pharyngeal, and laryngeal mucosa, with no skin involvement.     

Bullous pemphigoid antigen II (BP180) and its soluble extracellular domains are major autoantigens in mucous membrane pemphigoid: the pathogenic relevance to HLA class II alleles and disease severity

BACKGROUND: Mucous membrane pemphigoid (MMP), a chronic autoimmune subepithelial blistering disease, is associated with circulating IgG and/or IgA autoantibodies against several basement membrane zone antigens. The heterogeneity of clinical presentation and diversity of target autoantigens have contributed to difficulties in characterizing this condition immunologically. OBJECTIVES: To analyse serum autoantibody profile and HLA class II alleles in MMP patients and to correlate this with the clinical presentation of disease. METHODS: Well-defined subgroups consisting of 124 patients with MMP were examined for IgG and IgA reactivity with immunoblotting using human epidermal, dermal and placental amnion proteins. The results were further analysed on the basis of detailed clinical (sites of involvement and disease severity) and immunopathological criteria (immunofluorescence study and HLA class II alleles). RESULTS: Immunoblot assay revealed that the majority of MMP patients had IgG (93 of 124, 75%) and/or IgA autoantibodies (63 of 124, 51%) to BP180 (including its soluble ectodomains, 120-kDa LAD-1 and 97-kDa LABD97 antigens). Other antigens targeted predominantly by IgG autoantibodies included: BP230 in 34 (27%), beta4 integrin in 26 (21%), and laminin 5 in three (2%). All the BP230+ sera and 23 (88%) beta4 integrin+ sera also reacted with at least one of the BP180 antigens. Over 85% of patients with reactivity to beta4 integrin had ocular involvement. In most cases of MMP, more severe clinical features were associated with antibody reactivity to multiple basement membrane zone antigens, as well as reactivity to multiple BP180 component antigens. Dual BP180/LAD-1 reactivity with IgG and IgA was associated with a more severe phenotype. In addition, the subset-dependent autoantibody reactivity correlated well with specific HLA class II alleles, DQB1*0301, DRB1*04 and DRB1*11. CONCLUSIONS: Our results confirmed that BP180 is a major autoantigen targeted by the sera of patients with MMP. The disease-prevalent HLA class II alleles and humoral autoimmune response against the particular subsets of antigenic epitope(s) within BP180 ectodomain may contribute to the clinicopathological significance and disease severity of MMP.     

Detection of linear IgE deposits in bullous pemphigoid and mucous membrane pemphigoid: a useful clue for diagnosis

Summary Background Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease of the skin associated with IgG autoantibodies to BP180 and BP230, while mucous membrane pemphigoid (MMP) comprises a heterogeneous group of autoimmune blistering diseases characterized by a predominant mucous membrane involvement and scarring tendency associated with an autoantibody response to various autoantigens, including BP180. While the pathogenicity of IgG autoantibodies to BP180 has been demonstrated in BP, the role of IgE autoantibodies in mediating tissue damage in BP and MMP is unclear. Objectives To assess the presence of tissue‐bound IgE in patients with BP and MMP, and their correlation with distinct clinical features. Methods In this retrospective study, we assessed the presence of IgE deposits as detected by direct immunofluorescence microscopy of skin biopsy specimens obtained from 44 and 13 patients with a new diagnosis of BP and MMP, respectively. Distinct clinical features at time of diagnosis, such as itch, urticarial papules and plaques and eczematous lesions, were noted. Results In 18 of 44 (41%) patients with BP linear deposits of IgE of variable intensity were detectable along the dermoepidermal junction. In 14 (32%) of the cases, IgE deposits were found concomitantly with IgG and C3. In two (5%) patients, diagnosis of BP was based on the isolated detection of IgE together with consistent clinicopathological features. Nine of 13 (69%) patients with MMP also exhibited linear IgE deposits, including one case with isolated linear IgE deposits. Patients with BP with tissue‐bound IgE deposits had clinically significant urticarial papules and plaques when compared with patients with BP without IgE deposits. Conclusions Our findings indicate that demonstration of tissue‐bound IgE deposits provides an additional useful criterion for diagnosis of BP and MMP in some patients. Prospective studies are needed to better correlate the presence of tissue‐bound and circulating IgE autoantibodies and their specificity with distinct clinical features and course of BP and MMP.     

Anti-epiligrin cicatricial pemphigoid with IgG autoantibodies to the beta and gamma subunits of laminin 5

Anti-epiligrin cicatricial pemphigoid is an autoimmune subepithelial blistering disorder of mucous membranes and skin. By immunoblot analyses, sera of most patients with antiepiligrin cicatricial pemphigoid have been shown to react specifically with the alpha3 chain of laminin 5. We describe the first patient with anti-epiligrin cicatricial pemphigoid in whom circulating IgG autoantibodies directed against the beta3 and gamma2-chains of laminin 5 were detected. Treatment with oral prednisolone was beneficial in controlling the disease.     

Cicatricial pemphigoid: IgA and IgG autoantibodies target epitopes on both intra- and extracellular domains of bullous pemphigoid antigen 180

BACKGROUND: Cicatricial pemphigoid (CP) is an autoimmune subepidermal blistering disease where autoantibodies target various components of the dermal-epidermal junction, including the bullous pemphigoid antigen 180 (BP180). OBJECTIVE: We determined the exact specificity of circulating IgG and IgA autoantibodies to BP180 in a large number of CP patients. METHODS: Twenty-six consecutive CP sera were analysed by Western blotting using a panel of cell-derived and recombinant proteins covering the entire BP180 molecule. RESULTS: Circulating autoantibodies were detected in all CP sera. Seven sera reacting with laminin-5 were excluded from further analyses; the remaining 19 sera recognized BP180, including six sera (32%) that showed only IgA reactivity to this protein. With the combined use of the soluble BP180 ectodomain (LAD-1) and recombinant BP180 NC16A, 16 of these 19 CP sera (84%) targeted BP180. IgG reactivity was preferentially found against NC16A, whereas IgA antibodies predominantly recognized LAD-1. Thirty-two per cent of the BP180-reative sera revealed reactivity with the intracellular domain of this protein. CONCLUSIONS: Our findings demonstrate that autoantibodies in CP target epitopes on both extra- and intracellular domains of BP180 and highlight the importance of testing for both IgG and IgA reactivity in these patients' sera.     

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.     

Human orf complicated by epidermolysis bullosa acquisita

Orf is a DNA parapoxvirus transmitted to humans by contact with infected goats and sheep. Many complications have been reported after orf infection, including erythema multiforme. A few cases of autoimmune bullous dermatosis complicating orf disease have been reported to date. They are usually characterized by tense blister eruptions with or without mucosal involvement; linear deposition of C3, IgG and/or IgA along the basement membrane; and negativity of indirect immunofluorescence analysis and enzyme‐linked immunosorbent assay (ELISA) (performed in four of 11 reported cases). These analyses have targeted antigens of bullous pemphigoid, mucous membrane pemphigoid or epidermolysis bullosa acquisita, except one case of mucosal pemphigoid with antilaminin‐332 antibodies. We describe the case of a patient who presented with an ulceration on his finger 10 days after direct contact with a lamb during Eid al‐Adha. Four weeks later he developed a severe tense blistering eruption associated with mucous membrane erosions. Indirect immunofluorescence analysis using the patient's serum revealed circulating antibasement membrane IgG that bound the dermal side of salt‐split skin. ELISA was positive for recombinant immunodominant NC1 domain of type VII collagen. We finally diagnosed epidermolysis bullosa acquisita complicating probable human orf infection.     

Mucous membrane pemphigoid with immunoglobulin G autoantibodies against full-length and 120-kDa ectodomain of BP180

Mucous membrane pemphigoid (MMP) is a rare autoimmune, subepidermal, bullous disease characterized by erosive lesions on the mucous membranes and skin. MMP reacts with various target antigens including BP180, laminin-332, β4 integrin, α6 integrin or type VII collagen. We present a 67-year-old male MMP patient who had lesions on the oral and ocular mucous membranes and facial skin. By immunoblot analyses, immunoglobulin G autoantibodies in the patient's sera reacted with full-length BP180 and the 120-kDa ectodomain of BP180 (LAD-1).     

IgG, IgA and IgE autoantibodies against the ectodomain of desmoglein 3 in active pemphigus vulgaris

BACKGROUND: IgG autoantibodies against desmoglein (Dsg) 3 play a key part in the pathogenesis of pemphigus vulgaris (PV), the most severe autoimmune bullous disorder. OBJECTIVES: To determine whether immunoglobulin isotypes other than IgG are detectable in the sera of patients with PV and whether a particular immunoglobulin subtype is associated with a distinct clinical phenotype of PV. METHODS: Sera from 41 patients with acute-onset, chronic active, and remittent PV disease with mucosal and cutaneous lesions were assayed against a baculovirus-expressed Dsg3 protein by immunoblot analysis. RESULTS: In acute-onset PV, Dsg3-reactive IgG1 was detected in nine of 15 (60%), IgG4 in 14 of 15 (93%), IgA in nine of 15 (60%) and IgE in two of 15 (13%) sera. In chronic active PV, Dsg3-reactive IgG1 was detected in 11 of 18 (61%), IgG4 in 16 of 18 (89%), IgA in 13 of 18 (72%) and IgE in two of 18 (11%) sera. In contrast, sera from patients with remittent PV disease contained only Dsg3-reactive IgG1 in six of eight (75%) and IgG4 in four of eight (50%) cases, but not Dsg3-reactive IgA or IgE. CONCLUSIONS: In extension of previous findings, our study demonstrates that, in addition to IgG autoantibodies, IgA and occasionally IgE autoantibodies reactive with Dsg3 are present in acute and chronic active PV. The detection of Dsg3-reactive autoantibodies of the IgG4, IgA and IgE subclasses in active PV provides additional evidence that PV is a T-helper 2-regulated autoimmune disorder.     

Therapieresistentes Anti-Laminin-332-Schleimhautpemphigoid

Mucous membrane pemphigoid (MMP) is clinically characterized by predominant involvement of mucous membranes which in case of conjunctival lesions can lead to blindness. In MMP, autoantibodies are directed against different proteins of the dermal-epidermal junction; in 25% of cases, laminin 332 is the target. Anti-laminin 332 MMP with ocular involvement is particularly difficult to treat. A 46-year-old Caucasian man with anti-laminin 332 pemphigoid and extensive oral and nasal erosions as well as severe conjunctival involvement did not respond to intravenous dexamethasone-cyclophosphamide pulses combined with oral cyclophosphamide. After initiation of a therapeutic regimen originally established for the treatment of pemphigus, including immunoapheresis and rituximab in combination with intravenous dexamethasone-cyclophosphamide pulses and oral mycophenolate mofetil, lesions cleared within 4 months and circulating autoantibody levels became undetectable 3 months later. This is the first report of the successful use of adjuvant immunoapheresis and rituximab in previously treatment-refractory anti-laminin 332 MMP.     

Mapping the binding sites of anti-BP180 immunoglobulin E autoantibodies in bullous pemphigoid

Bullous pemphigoid (BP) is a subepidermal blistering disease characterized by autoantibodies against the hemidesmosomal protein BP180 (BPAg2, type XVII collagen). NC16A, a non-collagenous stretch of the BP180 ectodomain, is the primary target of pathogenic immunoglobulin (Ig)G autoantibodies and IgE class autoantibodies. This study further characterized the IgE-reactive regions of BP180. Of the ten sera from untreated BP patients, eight contained IgE reactive with the entire BP180 ectodomain. The IgE in four of these eight sera reacted with NC16A, whereas in the remaining four sera IgE immunoreactivity was restricted to sites downstream of NC16A. In contrast, IgG reactivity to NC16A was detected in nine of the ten BP sera, and in the remaining serum, IgG, as well as IgE, reacted exclusively with non-NC16A sites on the BP180 ectodomain. Fine mapping of the antigenic sites within NC16A revealed very similar reactivity patterns for IgE and IgG, with NC16A subregion-2 being the major site recognized by both isotypes. Eight of the untreated BP patients were tested for histamine release from their basophils in response to NC16A. Antigen-specific histamine release was observed only in those patients with detectable circulating IgE directed against NC16A (three of eight). Future studies will investigate the pathogenic relevance of anti-BP180 IgE.     

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.     

Pemphigoid gestationis with predominant involvement of oral mucous membranes and IgA autoantibodies targeting the C-terminus of BP180

Pemphigoid gestationis (PG) is an autoimmune pregnancy-associated subepidermal blistering disease. It usually affects skin and, rarely, mucous membranes. In the vast majority of patients with PG, the autoimmune response is directed to the membrane-proximal NC16A domain of the 180-kd bullous pemphigoid (BP) antigen (BP180) and is mediated by IgG1 and IgG3 autoantibodies. We report the case of a patient with PG associated with extensive lesions on oral mucous membranes. Immunoblotting studies demonstrated the presence of circulating IgA autoantibodies in the patient's serum that were exclusively directed to a 49 amino acid stretch on the C-terminal portion of the BP180 ectodomain located 800 amino acids downstream from NC16A. This C-terminal stretch of BP180 has previously been demonstrated to localize to the lamina lucida/lamina densa interface and to be recognized by IgG and IgA antibodies in a subgroup of patients with cicatricial pemphigoid as well as by IgG autoantibodies in some BP sera. Our patient's lesions healed without scarring within 6 weeks after delivery of a healthy child. The findings in this patient extend the clinical and immunopathologic spectrum of PG.     

Autoantibodies against desmocollins in European patients with pemphigus

Background. Autoimmune bullous disorders of the pemphigus group are characterized by autoantibodies targeting desmoglein (Dsg)1, Dsg3 and Dsg4 and occasionally, desmocollin (Dsc)1, Dsc2 and Dsc3. Both Dsg and Dsc are components of desmosomal adhesion complexes. Aim. To investigate the presence of IgG and IgA autoantibodies against Dsc1, Dsc2 and Dsc3 in a cohort of patients with bullous disorders. Methods. IgG and IgA autoantibodies against Dsc1, Dsc2 and Dsc3 were investigated by ELISA and immunoblotting analysis in a cohort of European patients with pemphigus vulgaris (PV; n = 74), IgA pemphigus (n = 3), paraneoplastic pemphigus (PNP; n = 3) and two cases of atypical pemphigus (n = 2). Results. Of the two cases with atypical pemphigus, one showed IgA reactivity against Dsc1 and Dsc3 and weak reactivity against Dsc2, and the other showed both IgG and IgA reactivity against Dsc1. One patient with IgA pemphigus had IgA autoantibodies against Dsc1, Dsc2 and Dsg1, and one patient with PNP had IgG reactivity against with Dsc3. In contrast, all the PV sera showed IgG reactivity against Dsg3 but not against Dsc1–3. Thus, IgG and IgA reactivity against Dsc was restricted to cases of PNP, IgA pemphigus and atypical pemphigus. Conclusions. These findings support the concept that desmocollins are not important autoantigens in PV.