LINEAR IGA DISEASE - A REPORT OF 2 DERMAL BINDING SERA WHICH RECOGNIZE A PEPSIN-SENSITIVE EPITOPE (NC-1 DOMAIN) OF COLLAGEN TYPE-VII

Linear IgA disease is a subepidermal blistering disease characterized by IgA autoantibody deposition at the basement membrane zone of skin a nd mucosa, The antigens targeted in linear IgA disease have been defin ed by their molecular weight and localization, It has bren proposed th at a minority of linear IgA disease sera that bind to the dermal aspec t of salt-split skin target collagen type VII. We hare identified two patients with linear IgA disease using dermal binding IgA autoantibodi es on salt-split skin which recognize collagen type VII by immunoblot analysis. The reactive epitope was destroyed by the proteolytic enzyme s pepsin, which destroys the NC-1 domain of collagen type VII, and pro tease type VIII, Localization studies compared the IgA autoantibodies from these patients with the monoclonal antibody LH7.2 to the NC-1 dom ain of collagen type VII and showed colocalization on a dermal cylindr oma tumour tissue, and a similar distribution with immunogold electron microscopy, using purified blister fluid from one patient, We propose from these results I-hat the IgA autoantibodies from these two patien ts recognize the NC-1 domain of collagen type VII, the classical immun odominant epitope for epidermolysis bullosa acquisita.