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Diagnosis of anti‐laminin γ‐1 pemphigoid by immunoblot analysis
Author(s) -
Solimani F.,
Pollmann R.,
Ishii N.,
Eming R.,
Hashimoto T.,
Schmidt T.,
Hertl M.
Publication year - 2019
Publication title -
journal of the european academy of dermatology and venereology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.655
H-Index - 107
eISSN - 1468-3083
pISSN - 0926-9959
DOI - 10.1111/jdv.15170
Subject(s) - bullous pemphigoid , epidermolysis bullosa acquisita , medicine , pemphigoid , autoantibody , serology , immunology , recombinant dna , antibody , cicatricial pemphigoid , autoimmunity , chemistry , biochemistry , gene
Background Anti‐laminin‐γ1 (lam‐γ1) pemphigoid, a recently described immunobullous disorder sharing immune serological features of bullous pemphigoid and epidermolysis bullosa acquisita ( EBA ), is characterized by the detection of serum IgG autoantibodies against the lam‐γ1 chain, a 200 kDa heterotrimeric component of the dermal‐epidermal junction ( DEJ ). Objective The aim of the study was to develop an easy‐to‐perform and reliable assay for the serological detection of anti‐lam‐γ1 IgG autoantibodies. The clinical appearance alone is not sufficient to establish diagnosis of anti‐lam‐γ1 pemphigoid and rather requires immune serological evidence of (i) IgG reactivity against the dermal portion of salt‐split human skin; (ii) exclusion of IgG against other components of the DEJ ; and (iii) IgG reactivity with a 200 kD a protein of dermal extracts by immunoblot analysis ( IB ). Methods The sera of 55 patients with anti‐lam‐γ1 pemphigoid were tested by IB with two recombinant heterotrimers, laminin 111 (lam‐111) and laminin 421 (lam‐421), as well as with a recombinant lam‐γ1 chain monomer. Additionally, a total of 41 control sera from patients with EBA ( n = 15), psoriasis vulgaris ( PV ; n = 14), and healthy controls ( HC ; n = 12) were tested. Results Immunoblot analysis revealed a positive reactivity with lam‐111 and/or lam‐421 in 46/55 (84%) of anti‐lam‐γ1 pemphigoid sera. Moreover, 8/9 of the initially non‐reactive sera were positive with the lam‐γ1 monomer, leading to an overall sensitivity of 98.2%. Analyses of 41 control sera with the three lam‐γ1 recombinants led to a specificity of 88%. Specifically, 3/15 EBA sera, 1/14 PV serum and 1/12 HC serum reacted with the lam‐γ1 monomer while only the 3 EBA sera reacted with lam‐421. Conclusions Here we show a novel two‐step IB assay using the two recombinant laminin trimers and lam‐γ1 chain monomer for the detection of anti‐lam‐γ1 serum IgG with high sensitivity and specificity. This assay will facilitate the diagnosis and further characterization of this disease.