A systematic review with pooled analysis of clinical presentation and immunodiagnostic testing in mucous membrane pemphigoid: association of anti-laminin-332 IgG with oropharyngeal involvement and the usefulness of ELISA.

BACKGROUND: Mucous membrane pemphigoid (MMP) is characterized by subepithelial blistering due to IgG autoantibodies targeting various components of the dermal-epidermal basement membrane zone. Immunodiagnostics play an important role in making a precise diagnosis. Measures of test sensitivity and specificity, however, typically come from studies in diseases such as bullous pemphigoid, where the exact antigenic site may not be the same. Additionally, the association of clinical phenotype and autoantibody profiles has been an area of debate.

OBJECTIVE: We evaluated the sensitivity and specificity of ELISA in MMP for the known target antigens BP180 and laminin-332, as well as characterized the frequency of IgG antibodies against each laminin-332 subdomain. Lastly, we analysed whether IgG auto-antibody profiles were associated with clinical phenotype.

METHODS: We performed a systematic review of Medline/PubMed to compile MMP patient demographics, clinical manifestations and immunodiagnostic results. ELISA sensitivities and specificities for autoantigens were calculated in patients with positive immunoblot or immunoprecipitationstudies. IgG reactivity for each laminin-332 subunit was recorded. Associations between positive immunological tests and clinical presentation were evaluated using chi-squared test tests or Fisher's exact test when appropriate.

RESULTS: For patients with a positive immunoblot or immunoprecipitation to NC16a, ELISA using both the NC16a and C-terminal portion of BP180 demonstrated a sensitivity and specificity of 73% and 93%. However, for individuals with IgG against the C-terminal domain of BP180, the sensitivity and specificity was 43% and 56%, respectively. LN-332 ELISA demonstrated 75% sensitivity, but only for patients with IgG reactivity against the α3 subunit. In patients with laminin-332 MMP, 86.4% demonstrated IgG against the α3 subunit. IgG autoantibodies against laminin-332 are significantly associated with pharyngo-laryngeal (P < 0.0001) and oro-pharyngo-laryngeal (P = 0.006) involvement.

CONCLUSIONS: Immunodiagnostics play a major role in diagnosing MMP, though limited sensitivity may necessitate several forms of testing for confirmation.