Auto-antibody-detection in oral-mucous-membrane-pemphigoid-patients specific to N-terminal-region of extracellular-domain of a6-integrin-subunit

Objectives: Mucous membrane pemphigoid (MMP), also known as cicatricial pemphigoid, is predominantly a mucosal disease that affects mucous membranes of the oral cavity, conjunctiva, nose, larynx, esophagus, anus and genitalia. Although this disease is characterized by the presence of pathogenic auto-antibodies of IgG class binding to different antigens, however, its prevalence, clinical relevance and target antigens remain unknown.

Methods: Dot blot analysis, Western blot analysis, emzyme linked immunosorbant assay (ELISA), indirect immunofluorescence (IIF) and direct immunofluorescence (DIF).

Results: In Dot blot and Western blot, we could confirm that the immunoreactivity of oral mucous membrane pemphigoid (OMMP) autoantibodies bind to a6 representing the N-terminal extracellular domain of 6 integrin subunit extending from 7aa to 562aa (61 kDa), baut not to the a6 integrin subunit extending from 556 aa to 1073 aa representing C-terminal extracellular domain (556aa-1011aa), transmembrane domain (1012aa-1037aa) and C-terminal intracellular domain (1038aa-1073aa). We provided the detection of the recombinant a6 integrin part I (a6 I), but not part II (a6 II), suggesting that the large majority of epitopes recognized by OMMP autoantibodies reside at the N-terminal region of the extracellular domain of a6 integrin subunit.

Conclusion: We provide for the first time evidence for the presence of an auto-antibody in OMMP sera that specifically recognizes N-terminal region of the extracellular domain of the a6 integrin subunit.