title: In vitro keratinocyte dissociation assay for evaluation of the pathogenicity of anti-desmoglein 3 IgG autoantibodies in pemphigus vulgaris.
abstract: Patients with pemphigus vulgaris (PV) have circulating anti-desmoglein (Dsg) 3 immunoglobulin G (IgG) autoantibodies that induce blister formation. We developed an in vitro quantitative assay to evaluate the pathogenic strength of anti-Dsg3 IgG autoantibodies in blister formation. To obtain intercellular adhesion mediated dominantly by Dsg3, we used primary cultured normal human keratinocytes expressing low level of Dsg2 in the presence of exfoliative toxin A that specifically digests Dsg1. After incubation with various antibodies, monolayers released by dispase were subjected to mechanical stress by pipetting, and the number of cell fragments were counted. When anti-Dsg3 monoclonal antibodies (mAb) obtained from pemphigus model mice were tested, pathogenic AK23 mAb yielded significantly higher number of cell fragments than AK7 or AK20 non-pathogenic mAb. Dissociation scores, defined with AK23 mAb as the positive control, were significantly higher with active stage PV sera (n=10, 77.4+/-21.4) than controls (n=11, 16.0+/-9.6; p=0.003). When pair sera obtained from 6 PV patients in active stage and in remission were compared, the dissociation scores reflected well the disease activity as those in active stage were four to 17 times higher than those in remission. When sera from different patients showing similar ELISA scores but different clinical severity were tested (n=6), the dissociation scores with sera from severe disease activity were significantly higher than those with sera in remission. These findings indicate that this dissociation assay will provide a simple and objective biological method to measure the pathogenic strength of pemphigus autoantibodies.
authors.affiliation: Department of Dermatology, Keio University School of Medicine, Tokyo, Japan. ken4ishii@aol.com
authors.forename: Ken
authors.initials: K
authors.lastname: Ishii
authors.forename: Reiko
authors.initials: R
authors.lastname: Harada
authors.forename: Itsuro
authors.initials: I
authors.lastname: Matsuo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Shirakata
authors.forename: Koji
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Amagai
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000633:toxicity*; D002448:Cell Adhesion; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000276:immunology*; D051183:Desmoglein 1; D051301:Desmoglein 2; D051182:Desmogleins; D051180:Desmoplakins; D004797:Enzyme-Linked Immunosorbent Assay; D005083:Exfoliatins / Q000494:pharmacology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000633:toxicity*; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010392:Pemphigus / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D003598:Cytoskeletal Proteins; C495297:DSG1 protein, human; C495314:DSG2 protein, human; D051183:Desmoglein 1; D051301:Desmoglein 2; D051182:Desmogleins; D051180:Desmoplakins; D005083:Exfoliatins; D007074:Immunoglobulin G