Skin autoantibodies

Role

A defined panel of autoantibodies supports diagnosis of autoimmune bullous disease and connective tissue disease with cutaneous involvement - each antibody targeting a specific structural or nuclear antigen, with the target correlating closely with clinical phenotype
Ordered whenever a blistering eruption or a photosensitive/connective-tissue-suggestive rash raises suspicion for an autoimmune dermatosis, complementing skin biopsy with direct immunofluorescence (see skin biopsy)

Desmoglein 1/3 - target antigens in pemphigus (desmosomal proteins) - antibody titre correlates with disease activity, useful for monitoring as well as diagnosis
BP180/BP230 - target antigens in bullous pemphigoid (hemidesmosomal proteins)
ANA/ENA (anti-Ro/SSA, anti-La/SSB) - relevant to cutaneous/subacute lupus and photosensitive rashes
Anti-epidermal transglutaminase/anti-tissue transglutaminase - dermatitis herpetiformis, linking to underlying coeliac disease

Serum autoantibody testing complements skin biopsy with direct immunofluorescence - a positive serum antibody supports but does not alone confirm the diagnosis, which should integrate clinical phenotype, biopsy histology, and immunofluorescence pattern

Result interpretation is diagnosis-specific: desmoglein antibody titre tracks pemphigus disease activity and can guide treatment adjustment, while ANA/ENA results (in the context of a photosensitive rash) prompt assessment for systemic lupus erythematosus beyond the skin alone

Pemphigus vulgaris (desmoglein 1/3), bullous pemphigoid (BP180/BP230), dermatitis herpetiformis (anti-transglutaminase, coeliac association), subacute cutaneous/systemic lupus (anti-Ro/SSA)
Autoantibody target correlates tightly with clinical blister depth and phenotype - desmosomal antibodies (pemphigus) produce intraepidermal, flaccid blisters, while hemidesmosomal antibodies (pemphigoid) produce subepidermal, tense blisters - a mechanistic link that directly explains the differing clinical appearance of the two conditions

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