Diagnosis and disease severity assessment of epidermolysis bullosa acquisita by ELISA for anti-type VII collagen autoantibodies: an Italian multicentre study.

Epidermolysis bullosa acquisita (EBA) is a rare autoimmune mucocutaneous bullous disease caused by autoantibodies against type VII collagen, a component of anchoring fibrils that stabilizes dermoepidermal adherence. Type VII collagen is composed of a collagenous domain linked by the noncollagenous (NC)1 and NC2 domains.  To assess the repeatability, sensitivity and specificity of a recently developed enzyme-linked immunosorbent assay (ELISA) for detection of anti-type VII collagen autoantibodies, and to ascertain whether they may be a marker of disease activity in EBA. Using this ELISA, which was able to recognize autoantibodies against the NC1 and NC2 epitopes of type VII collagen, we tested 14 EBA sera, 30 healthy control sera and 113 disease control sera. In the EBA sera group, 12 out of the 14 samples were positive in ELISA, with autoantibody titres varying from 7·2 to 127·9UmL(-1) (cutoff value <6), the sensitivity of the method being 86%. Among the controls, only two bullous pemphigoid sera tested positive, the specificity being 98·6%. A good correlation was found between EBA disease severity, expressed as autoimmune bullous skin disorder intensity score, and the serum levels of anti-collagen VII autoantibodies, measured by ELISA (n =14; r=0·965; P=0·0001). The intra- and interassay coefficients of variation of the ELISA method ranged from 6·3% to 18·3%.  This NC1+NC2 ELISA can be a practical assay for the diagnosis of EBA. The correlation between autoantibody titres and disease severity suggests its usefulness as a marker of disease activity in EBA However, this should be confirmed by studies on larger series of patients.

Marzano AV ，Cozzani E ，Fanoni D ，De Pità O ，Vassallo C ，Berti E ，Parodi A ，Crosti C ，Cugno M ... -  《-》

Serum levels of anti-type VII collagen antibodies detected by enzyme-linked immunosorbent assay in patients with epidermolysis bullosa acquisita are correlated with the severity of skin lesions.

Epidermolysis bullosa acquisita (EBA) is a chronic autoimmune subepidermal bullous disease characterized by circulating autoantibodies against type VII collagen. Detecting these autoantibodies is crucial for the diagnosis of this disease, and is also useful for measuring disease activity. Enzyme-linked immunosorbent assay (ELISA), a quantitative method to measure anti-type VII collagen antibody levels, is currently available to diagnose EBA. The aim of this study was to investigate the relationship of ELISA with overall clinical severity. Sera from patients with EBA (n = 30), bullous pemphigoid (n = 20), anti-laminin γ1 pemphigoid (n = 9) and healthy donors (n = 24) were tested using ELISA, using the recombinant non-collagenous 1 (NC1) and 2 (NC2) domains of type VII collagen. Relationships between clinical characteristics, indirect immunofluoroscence (IIF) titres and ELISA values were investigated. The sensitivity and specificity of the EBA ELISA were 96.7% and 98.1%, respectively. There was no significant difference between ELISA results for classic and inflammatory types. The severity of skin involvement was positively correlated with both ELISA value (r = 0.87, P < 0.01) and IIF titre (r = 0.59, P < 0.01). Time sequence analysis in four patients with EBA showed that ELISA values reflect disease activity better than IIF titres. Type VII collagen ELISA using the NC1 and NC2 domains is useful for diagnosing EBA and monitoring disease severity.

Kim JH ，Kim YH ，Kim S ，Noh EB ，Kim SE ，Vorobyev A ，Schmidt E ，Zillikens D ，Kim SC ... -  《-》

Comparison of 3 type VII collagen (C7) assays for serologic diagnosis of epidermolysis bullosa acquisita (EBA).

Serologic diagnosis of epidermolysis bullosa acquisita (EBA) relies on the detection of circulating autoantibodies to type VII collagen (C7). We sought to compare the diagnostic performances of a commercialized enzyme-linked immunosorbent assay (ELISA) using C7 noncollagenous (NC) domains (C7-NC1/NC2 ELISA) and indirect immunofluorescence (IIF) biochip test on NC1-C7-expressing transfected cells (IIFT), with a full-length-C7 ELISA developed in our laboratory. C7-NC1/NC2 ELISA, IIFT, and full-length-C7 ELISA were run on 77 nonselected consecutive EBA sera. C7-NC1/NC2 ELISA, IIFT, and full-length-C7 ELISA were positive, respectively, for: 30%, 27%, and 65% of the 77 sera; 43%, 32%, and 80% of 44 sera labeling the salt-split-skin (SSS) floor (F) by IIF (SSS/F(+)); 9%, 22%, and 47% of 32 SSS/F(-) sera; 28%, 28%, and 58% of classic EBA; 41%, 41%, and 82% of inflammatory EBA; and 18%, 0%, and 55% of mucous-membrane-predominant EBA. Significant differences for all sera were found between: the 2 ELISAs for the 77 sera, SSS/F(+) and SSS/F(-) sera, and IIFT versus full-length-C7 ELISA. The retrospective design was a limitation. C7-NC1/NC2 ELISA and IIFT sensitivities for serologic diagnoses of EBA were low. Full-length-C7 ELISA was significantly more sensitive and could serve as a reference test.

Seta V ，Aucouturier F ，Bonnefoy J ，Le Roux-Villet C ，Pendaries V ，Alexandre M ，Grootenboer-Mignot S ，Heller M ，Lièvre N ，Laroche L ，Caux F ，Titeux M ，Hovnanian A ，Prost-Squarcioni C ... -  《-》

Serological diagnostics in the detection of IgG autoantibodies against human collagen VII in epidermolysis bullosa acquisita: a multicentre analysis.

Epidermolysis bullosa acquisita (EBA) is a rare, potentially devastating autoimmune disease of the skin. IgG autoantibodies directed against type VII collagen (Col7), the major component of anchoring fibrils, induce skin fragility leading to cutaneous and mucocutaneous blister formation, which is mostly of a scarring phenotype. Thus, powerful and reproducible diagnostic assays are critical to establish the diagnosis of EBA early to avoid irreversible sequelae. The present international, retrospective multicentre study included a large cohort of patients with EBA and evaluated the diagnostic power of four different diagnostic assays for the detection of anti-Col7 IgG autoantibodies. Overall, 95 EBA sera and 200 control sera consisting of 100 bullous pemphigoid sera, 50 pemphigus vulgaris sera and 50 sera of healthy controls were tested for anti-Col7 IgG autoantibodies using indirect immunofluorescence (IIF), two commercial enzyme-linked immunosorbent assay (ELISA) systems and Western blot (WB) analysis. EBA sera were taken from patients with positive direct immunofluorescence and IgG reactivity in at least one of the immunoserological assays (IIF, ELISA, WB). A Col7-NC1/NC2 ELISA (MBL, Nagoya, Japan) showed the highest sensitivity (97·9%), followed by a Col7-NC1 ELISA (Euroimmun, Lübeck, Germany) (89·5%), WB with Col7-NC1 (85·3%), and IIF on saline-split human skin (74·7%). The specificities of both ELISA systems were comparable (NC1 98·7%, NC1/NC2 99·3%). Furthermore, WB was more sensitive than IIF, which was more specific. The two commercially available ELISA systems allow for a highly sensitive and specific diagnosis of EBA. The sensitivity of the Col7-NC1/NC2 ELISA is significantly higher compared with the ELISA based on the Col7-NC1 domain only.

Schmidt T ，Hoch M ，Lotfi Jad SS ，Solimani F ，Di Zenzo G ，Marzano AV ，Goebeler M ，Cozzani E ，Kern JS ，Sitaru C ，Lakoš Jukić I ，Sárdy M ，Uzun S ，Jedlickova H ，Gläser R ，Kaneda M ，Eming R ，Göpel G ，Ishii N ，Greene B ，Hashimoto T ，Hertl M ... -  《-》

Sensitive and specific assays for routine serological diagnosis of epidermolysis bullosa acquisita.

Epidermolysis bullosa acquisita (EBA) is a severe autoimmune subepidermal blistering disease characterized by autoantibodies against the N-terminal collagenous domain (NC1) of type VII collagen (Col VII). Development of reliable assays for the detection of anti-Col VII-NC1 antibodies. NC1 was expressed in human HEK293 cells and used as target antigen in an enzyme-linked immunosorbent assay (ELISA) and in an immunofluorescence assay (IFA). These two assays were probed in a large cohort of patients with EBA (n = 73), bullous pemphigoid (BP, n = 72), anti-p200 pemphigoid (n = 24), anti-laminin 332 mucous membrane pemphigoid (MMP, n = 15), pemphigus vulgaris (PV, n = 24), and healthy control subjects (n = 254). The cut-off for the ELISA was optimized for accuracy by receiver-operating characteristics (area under the curve [AUC] = 0.9952). IgG reactivity against NC1 was detected in 69 of 73 EBA (94.5%) and 5 control sera (2 healthy controls and 3 BP patients), resulting in a specificity of 98.7%. The IFA showed a sensitivity of 91.8% and specificity of 99.8%. Reproducibility of the ELISA was demonstrated by an intra-class correlation coefficient of 0.97. IgG subclass analyses by ELISA revealed IgG1, IgG2, IgG3, and IgG4 anti-NC1 reactivity in 83.6%, 85.3%, 37.7%, and 83.6% of EBA sera, respectively. The novel assays were not evaluated prospectively and their use in monitoring serum levels during the disease course was not tested. The two assays are highly specific and sensitive to diagnose EBA. Their diagnostic competence was demonstrated in a large cohort of well-characterized EBA sera.

Komorowski L ，Müller R ，Vorobyev A ，Probst C ，Recke A ，Jonkman MF ，Hashimoto T ，Kim SC ，Groves R ，Ludwig RJ ，Zillikens D ，Stöcker W ，Schmidt E ... -  《-》