Skin Immunofluorescence Studies

Direct immunofluorescence studies, i.e., looking for the presence of deposits of immunoglobulin and complement in specific locations within a skin biopsy, can play an important role in the identification of specific dermatides. For example: granular deposits of IgA at the dermal-epidermal junction are the sine qua non of dermatitis herpetiformis; the presence of IgG deposits in a 'chicken wire' pattern within the epidermis is characteristic of the pemphigus family of disorders; and bullous pemphigoid is characterized by linear deposits of IgG at the dermal-epidermal junction.

Indirect immunofluorescence, using the patient's serum, can yield important information regarding the titer of circulating antibodies to desmoglein proteins ('intercellular substance') characteristic of pemphigus. Using a 'salt split skin' preparation, in which a biopsy of skin from a normal individual is artificially 'split' using a high salt solution, it is possible to distinguish between bullous pemphigoid (BP) and epidermalysis bullosa (EBA), which can yield identical direct immunofluorescence patterns of linear IgG deposits at the dermal-epidermal junction. In the 'salt split skin' preparation, the hemidesmosomal protein identified by circulating antibodies in patients with BP is present on the roof of the induced separation, whereas the serum of EBA patients contains antibodies which react with proteins present in the floor of the separated skin preparation. A summary of the principal direct and indirect immunofluorescence findings appears in the table on the following page.

Note: Skin immunofluorescence studies require unfixed biopsy material. Biopsies can be stored up to 72 hours in Transport Media that ranges in pH from 7 to 7.5. Please contact PhenoPath and we will be happy to supply you with Transport Media and kits for sending specimens to the laboratory.

	Disorder	Direct IF Findings	Indirect (Serum) IF Findings
	Bullous pemphigoid	Linear C3 and IgG at basement membrane zone	Circulating antibodies to basement membrane zone (60-70%) [hemidesmosomal proteins Bp180, BP230]
	Chronic bullous disease of childhood	Linear IgA at basement membrane zone	Circulating IgA to basement membrane zone (60%)
	Cicatricial pemphigoid	Linear C3 and IgG at basement membrane zone	Circulating antiodies to basement membrane zone (20-40%)
	Dermatitis herpetiformis	Granular IgA deposits in superficial papillary dermis (80%)	Generally negative (except in linear IgA variant)
	Epidermolysis bullosa acquisita	Linear IgG at basement membrane zone	Circulating IgG against basement membrane zone [EBA antigen]
	Herpes gestationis	Linear C3 at basement membrane zone (30%)	Circulating 'HG factor' against basement membrane zone (90%)
	Lupus erythematosis	Granular IgM (and others) at basement membrane zone ('lupus band')	Antinuclear antibodies
	Pemphigus	'Chicken wire' pattern of IgG in epidermis	Circulating IgG against intercellular substances [desmoglein-1, desmoglein-3]

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