Autoimmunity to type VII collagen.

The epidermolysis bullosa acquisita (EBA) antigen is type VII collagen that is found within the anchoring fibrils of the basement membrane zone beneath stratified epithelia. Autoimmunity to the EBA antigen/type VII collagen has been associated with three diseases: EBA, bullous systemic lupus erythematosus (SLE) and a subset of linear IgA bullous diseases. Although some systemic diseases in which autoimmunity is thought to play a role (eg, inflammatory bowel disease, thyroiditis) have been reported in association with EBA, so far there have not been systemic diseases associated with autoimmunity to type VII collagen other than SLE. In the case of EBA and bullous SLE, it appears that many patients may have a genetic predisposition toward autoimmunity because they share a human leukocyte antigen (HLA) major histocompatibility (MHC) class II cell surface protein, HLA-DR2. The full clinical spectrum of EBA and perhaps other diseases in which there is an association with autoimmunity to type VII collagen is currently being defined.