Ultrastructural localization of in vivo-bound complement in bullous pemphigoid.

Antihuman complement component C3 labeled with horseradish peroxidase was used to reveal the ultrastructural localization of complement in two cases of bullous pemphigoid. The complement deposits were shown to be exclusively located in the space between the plasma membrane of the basal cells and the basal lamina. This corresponds exactly to the ultrastructural localization of immunoglobulins in bullous pemphigoid.