A HIGHLY SENSITIVE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THE DETECTION OF CIRCULATING ANTI-BP180 AUTOANTIBODIES IN PATIENTS WITH BULLOUS PEMPHIGOID

The BP180 antigen, a component of the epidermal anchoring complex, has been identified as one of the major antigenic targets of autoantibodi es associated with the blistering skin disease, bullous pemphigoid, Ou r research group has recently demonstrated that reactivity of bullous pemphigoid autoantibodies to the BP180 ectodomain is almost entirely r estricted to a set of four antigenic sites clustered within the membra ne-proximal noncollagenous stretch (NC16A), Using a passive transfer m ouse model, antibodies to the corresponding noncollagenous region of m urine BP180 were shown to trigger an inflammatory subepidermal blister ing disease that closely mimics bullous pemphigoid, We now report the development of an enzyme-linked immunoabsorbent assay system that is e xtremely sensitive in detecting disease-specific autoantibodies in the sera of bullous pemphigoid patients. The target antigen in this assay is a recombinant form of the BP180 NC16A domain that contains all fou r of the well-defined bullous pemphigoid-associated antigenic sites, O f 50 randomly selected bullous pemphigoid sera tested, 47 (94%) were p ositive in this assay, whereas no specific reactivity was detected in any of the 107 controls, Interestingly, all three of the bullous pemph igoid sera that were negative in this assay had been obtained from pat ients who were already undergoing treatment, The NC16A enzyme-linked i mmunosorbent assay is more sensitive than any of the standard techniqu es for detecting circulating bullous pemphigoid autoantibodies, includ ing other enzyme-linked immunosorbent assays, immunoblotting, and indi rect immunofluorescence, Finally, the NC16A enzyme-linked immunosorben t assay provides immunologic information that cannot be obtained from direct immunofluorescence studies of skin biopsies, and that may well be relevant in the diagnosis and treatment of bullous pemphigoid.