Diagnostic value of indirect immunofluorescence on sodium chloride-split skin in differential diagnosis of subepidermal autoimmune bullous dermatoses.

International audienceOBJECTIVE: To determine the diagnostic value of indirect immunofluorescence on sodium chloride-split skin (SSS) in differentiating the pemphigoid group of subepidermal autoimmune bullous dermatoses, including bullous pemphigoid (BP), cicatricial pemphigoid, and pemphigoid gestationis, from epidermolysis bullosa acquisita (EBA). DESIGN: Serum samples were tested using immunofluorescence on SSS and immunoblot assay on epidermal and dermal extracts, a recombinant protein corresponding to the C-terminal end of the 230-kd BP antigen, and purified laminin-5. SETTING: An immunodermatology laboratory. PATIENTS: One hundred forty-two serum samples from patients with BP (n = 98), cicatricial pemphigoid (n = 23), pemphigoid gestationis (n = 10), EBA (n = 10), and anti-type IV collagen (n = 1). MAIN OUTCOME MEASURES: Binding sites of serum to the epidermal and/or dermal sides of SSS were correlated with their antigenic specificities. RESULTS: Epidermal staining on SSS was highly specific for pemphigoid. Alternatively, a poor correlation was found for the dermal-reacting serum samples and the diagnosis of EBA; of the 19 serum samples with dermal staining on SSS, only 10 reacted with the EBA antigen. The remaining serum samples were from patients with cicatricial pemphigoid having antibodies to the alpha 3 or beta 3 chains of laminin-5 (n = 5) or patients with BP having antibodies to the 180-kd BP antigen (n = 2). One sample recognized exclusively a 185-kd dermal antigen corresponding to type IV collagen. One more BP serum sample with dermal staining did not recognize any dermal or epidermal antigen. CONCLUSION: In case of immunofluorescent dermal staining, the precise diagnosis should be confirmed by identification of the involved antigen, since it may reveal antibodies to laminin-5 or type XVII or IV collagen, in addition to the EBA antigen.OBJECTIVE: To determine the diagnostic value of indirect immunofluorescence on sodium chloride-split skin (SSS) in differentiating the pemphigoid group of subepidermal autoimmune bullous dermatoses, including bullous pemphigoid (BP), cicatricial pemphigoid, and pemphigoid gestationis, from epidermolysis bullosa acquisita (EBA). DESIGN: Serum samples were tested using immunofluorescence on SSS and immunoblot assay on epidermal and dermal extracts, a recombinant protein corresponding to the C-terminal end of the 230-kd BP antigen, and purified laminin-5. SETTING: An immunodermatology laboratory. PATIENTS: One hundred forty-two serum samples from patients with BP (n = 98), cicatricial pemphigoid (n = 23), pemphigoid gestationis (n = 10), EBA (n = 10), and anti-type IV collagen (n = 1). MAIN OUTCOME MEASURES: Binding sites of serum to the epidermal and/or dermal sides of SSS were correlated with their antigenic specificities. RESULTS: Epidermal staining on SSS was highly specific for pemphigoid. Alternatively, a poor correlation was found for the dermal-reacting serum samples and the diagnosis of EBA; of the 19 serum samples with dermal staining on SSS, only 10 reacted with the EBA antigen. The remaining serum samples were from patients with cicatricial pemphigoid having antibodies to the alpha 3 or beta 3 chains of laminin-5 (n = 5) or patients with BP having antibodies to the 180-kd BP antigen (n = 2). One sample recognized exclusively a 185-kd dermal antigen corresponding to type IV collagen. One more BP serum sample with dermal staining did not recognize any dermal or epidermal antigen. CONCLUSION: In case of immunofluorescent dermal staining, the precise diagnosis should be confirmed by identification of the involved antigen, since it may reveal antibodies to laminin-5 or type XVII or IV collagen, in addition to the EBA antigen

Identification of a 168-kDa mucosal antigen in a subset of patients with cicatricial pemphigoid.

International audienceThis study describes the presence of antibodies in sera from patients with cicatricial pemphigoid specific for a 168-kDa antigen expressed by buccal mucosa. Six cicatricial pemphigoid sera unreactive, with epidermal or dermal proteins in immunoblot assay were tested on mucosal protein extracts. Four of these sera labeled a mucosal 168-kDa antigen (M168) under reducing conditions. An additional cicatricial pemphigoid serum with circulating antibodies to 180-kDa bullous pemphigoid antigen (BPAg2) also labeled M168. None of these cicatricial pemphigoid sera reacted with the alpha, beta, or gamma subunits of laminin-5. Nitrocellulose elution studies showed that the M168 antigen is a basement membrane antigen and labeled the epidermal side of salt-split skin. Immunoaffinity-purified anti-M168 antibodies did not bind to the 230-kDa bullous pemphigoid antigen (BPAg1) or to the 180-kDa BPAg2. None of the control sera from healthy individuals or from bullous pemphigoid, pemphigus vulgaris, or pemphigus foliaceus patients reacted with Ml68. This study demonstrates the specificity of some cicatricial pemphigoid sera against a 168-kDa antigen that is different from the laminin-5 subunits and shares no epitopes with the antigens of bullous pemphigoid (BPAg1, BPAg2) or the epidermolysis bullosa acquisita.This study describes the presence of antibodies in sera from patients with cicatricial pemphigoid specific for a 168-kDa antigen expressed by buccal mucosa. Six cicatricial pemphigoid sera unreactive, with epidermal or dermal proteins in immunoblot assay were tested on mucosal protein extracts. Four of these sera labeled a mucosal 168-kDa antigen (M168) under reducing conditions. An additional cicatricial pemphigoid serum with circulating antibodies to 180-kDa bullous pemphigoid antigen (BPAg2) also labeled M168. None of these cicatricial pemphigoid sera reacted with the alpha, beta, or gamma subunits of laminin-5. Nitrocellulose elution studies showed that the M168 antigen is a basement membrane antigen and labeled the epidermal side of salt-split skin. Immunoaffinity-purified anti-M168 antibodies did not bind to the 230-kDa bullous pemphigoid antigen (BPAg1) or to the 180-kDa BPAg2. None of the control sera from healthy individuals or from bullous pemphigoid, pemphigus vulgaris, or pemphigus foliaceus patients reacted with Ml68. This study demonstrates the specificity of some cicatricial pemphigoid sera against a 168-kDa antigen that is different from the laminin-5 subunits and shares no epitopes with the antigens of bullous pemphigoid (BPAg1, BPAg2) or the epidermolysis bullosa acquisita