Ultrastructural localization of immunoglobulins in bullous pemphigoid skin. Employment of a new peroxidase-antiperoxidase multistep method.

A multistep immunochemical method was developed for light and electron microscopy utilizing horseradish peroxidase as an immunologically bound marker. The method was applied to studies of in vivo bound IgG in bullous pemphigoid skin and of circulating antibasement membrane antibodies using rhesus esophagus as substrate. The immunocytochemical chain employed consisted of sequential binding of goat antihuman IgG, rabbit antigoat IgG, goat antihorseradish peroxidase antibody, and horseradish peroxidase. The sites of the latter were revealed cytochemically. At the light microscope level, results closely paralleled those obtained with regular immunofluorescence. With the electron microscope, IgG deposits were shown to be confined to the basal lamina and lamina lucida including the basilar surface of basal cells. Immunoglobulin deposits in bullous pemphigoid appear to be a true basal lamina phenomenon.