Antiplectin autoantibodies in subepidermal blistering diseases.

[epidermolysis bullosa simplex]

Hemidesmosomal proteins may become targets of autoimmunity in subepidermal blistering diseases . Well-known recognized autoantigens are the intracellular plaque protein BP 230 , the transmembrane BP 180 and its shed ectodomain LAD -1 .To establish the prevalence of autoimmunity against plectin , another intracellular plaque protein , and to investigate its antigenic sites .Two hundred and eighty-two patients with subepidermal blistering diseases , investigated by routine immunoblot analysis for possible antiplectin antibodies , were included in the study . Epitope mapping was performed using recombinantly produced overlapping plectin domains from the actin-binding domain to the rod domain . The COOH-terminal region of plectin was not included in the study .In 11 of 282 (3 .9 %) patients an immunoblot staining pattern identical to that of antiplectin monoclonal antibody HD 121 was found . Affinity-purified antibodies bound back to normal human skin in a pattern typical for plectin , i .e . to the epidermal basement membrane zone as well as to keratinocytes in the epidermis , and to myocytes . No binding was seen to plectin -deficient skin of a patient with epidermolysis bullosa simplex with muscular dystrophy . Epitope mapping of the plectin molecule showed that the central coiled-coil rod domain is an immunodominant hotspot as 92 % of the sera with antiplectin antibodies reacted with it . Most patients with antiplectin antibodies also had antibodies to other pemphigoid antigens .P lectin is a minor pemphigoid antigen with an immunodominant epitope located on the central rod domain .