What is the role of direct immunofluorescence (DIF) in the workup of pemphigus vulgaris?

Updated: Sep 17, 2020
  • Author: Bassam Zeina, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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DIF demonstrates in vivo deposits of antibodies and other immunoreactants, such as complement. DIF usually shows immunoglobulin G (IgG) deposited on the surface of the keratinocytes in and around lesions. IgG1 and IgG4 are the most common subclasses. Complement components such as C3 and immunoglobulin M are present less frequently than IgG. DIF shows intercellular deposition throughout the epidermis. This pattern of immunoreactants is not specific for pemphigus vulgaris and may be seen in pemphigus vegetans, pemphigus foliaceus, and pemphigus erythematosus. The best location for DIF testing is on normal perilesional skin. When DIF testing is performed on lesional skin, false-positive results can be observed. DIF results are shown in the image below.

Direct immunofluorescence showing intercellular im Direct immunofluorescence showing intercellular immunoglobulin G throughout the epidermis of a patient with pemphigus vulgaris.

Skin biopsy specimens placed in transport media may yield false-negative results; therefore, fresh tissue is the preferred substrate for DIF studies.

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