Immunochemical localization of in vivo bound immunoglobulins in pemphigus vulgaris epidermis. Employment of a peroxidase-antiperoxidase multistep technique for light and electron microscopy.

A multi-step immunocytochemical method utilizing horseradish peroxidase (HRP) as an immunological marker was employed to demonstrate, at the ultrastructural level, IgG antiepithelial autoantibodies bound in vivo to pemphigus epidermis, and circulating IgG antibodies, using monkey oesophagus as substrate. To demonstrate IgG the following antisera were employed in sequential steps: Goat antihuman IgG; rabbit antigoat IgG; goat-anti-HRP-serum. After incubating with the final antigen, HRP, the latter was visualized with a cytochemical method. Results paralleled those obtained by immunofluorescence, the antiepithelial antibody being demonstrated at the sites of the intercellular spaces of the epidermis. Electron microscopic cytochemistry showed IgG in the surface coat of epidermal cells and in the intercellular space, both in the desmosomal and the interdesmosomal areas. These results confirm the results of a previous study but the localization of the antibody is more exact than that obtained with HRP-conjugates. The present method is more versatile and specific than HRP methods that utilize HRP-conjugated antibodies.