A case of bullous pemphigoid associated with autoantibodies targeting antigenic sites other than the NC16a domain of BP180.

Bullous pemphigoid (BP) is associated with autoantibodies to the 180-kDa BP antigen (BP180), and the antigenic site exists on noncollagenous 16a (NC16a) domain of BP180. We now report a male BP patient whose IgG autoantibodies did not react against the NC16a domain of BP180 by either immunoblotting or ELISA, whereas they did react with BP180 extracted from normal human keratinocytes. Anti-BP180 cicatricial pemphigoid was ruled out due to the lack of conjunctival mucosal involvement and the absence of scarring in the oral cavity. Our findings indicate that there is an antigenic reactive region other than NC16a on the extracellular domain of BP180. There have been few reports describing detailed clinical features of BP caused by autoantibodies targeting antigenic sites other than the NC16a domain. We conclude that it is difficult to differentiate their clinical features from those associated with autoantibodies targeting the NC16a domain of BP180.