Anti-p200 pemphigoid.

Anti-p200 pemphigoid is a rare subepidermal blistering skin disease. Patients' autoantibodies label the dermal side of 1 mol/L NaCl-split human skin by indirect immunofluorescence microscopy and recognize a 200-kd protein by immunoblotting of human dermal extract. Clinically, anti-p200 pemphigoid is characterized by tense blisters and vesicles, erosions, and urticarial plaques, closely resembling bullous pemphigoid and the inflammatory variant of epidermolysis bullosa acquisita. Recently, 90% of anti-p200 pemphigoid sera were shown to recognize laminin γ1. The C-terminus of laminin γ1 was identified as an immunodominant region and in its recombinant form was used by immunoblotting and enzyme-linked immunosorbent assay for the serologic diagnosis of this disease. Subsequent ex vivo and in vivo studies were, however, unable to show pathogenic activity of antilaminin γ1 antibodies. Both patients' sera and sera depleted from antilaminin γ1 antibodies induced subepidermal splitting in an ex vivo model of autoantibody-mediated leukocyte-dependent neutrophil activation. Antilaminin γ1 antibodies appear to be useful biomarkers that will further facilitate the diagnosis of anti-p200 pemphigoid. The true identity of the pathogenetically relevant autoantigen of this disease, which may either be a yet unknown isoform of laminin γ1 or even another 200-kd protein of the dermoepidermal junction, still needs to be elucidated.