Autoantibody Detection for Diagnosis in Direct Immunofluorescence-Negative Mucous Membrane Pemphigoid

Purpose: To assess whether a panel of serum pemphigoid autoantibody tests could be used to confirm an immunopathologic diagnosis of mucous membrane pemphigoid (MMP) in direct immunofluorescent negative (DIFe) MMP patients. Design: Prospective cross-sectional study. Participants: Seventy-six patients with multisite MMP with 45 matched control participants. Methods: Enzyme-linked immunosorbent assays (ELISAs) for BP180 and BP230 (MBL International), immunoglobulin A (IgA) A and immunoglobulin G indirect immunofluorescence (IIF) on human salt-split skin and the keratinocyte footprint assay for antielaminin 332 antibodies. Main Outcome Measures: Sensitivity and specificity of autoantibody detection and significant differences for individual tests and test combinations for MMP involving different sites. Results: All DIFe patients (24/73 [31.8%]) had either ocular-only disease or ocular involvement in multisite disease. Serum pemphigoid autoantibodies were detected in 29 of 76 MMP patients (38.2%) compared with 3 of 45 control participants (6.7%). Autoantibody reactivity detected by any 1 or more of the tests was present in 6 of 24 DIFe patients (25%) compared with 22 of 49 DIF positive (DIFthorn) patients (44.9%). Ocular-only MMP serum reactivity was not significantly different for any test or test combination compared with control participants, whereas DIFe multisite ocular MMP differed for 1 ELISA and 3 of 7 test combinations. By contrast, for DIFthorn nonocular MMP patients, all the individual tests, apart from IgA IIF, and all test combinations were significantly different compared with those for control participants. For the entire MMP cohort, the sensitivity of all individual tests was low, having a maximum of 21.05% for BP180 reactivity but increasing to 38.16% for an optimal test combination. Disease activity was associated strongly with positive serologic findings. Conclusions: Pemphigoid serum autoantibody tests did not provide immunopathologic evidence of MMP in ocular-only MMP patients but showed limited value in DIFe multisite ocular MMP patients. The requirement for immunopathologic confirmation of MMP by autoantibody detection is inappropriate for DIFe ocular-only MMP patients, resulting in missed diagnoses, delayed therapy, and poor outcomes. Alternative diagnostic criteria for ocular-only MMP are required to exclude the other causes of scarring conjunctivitis until more sensitive and specific immunopathologic tests become available. Ophthalmology 2021;128:372-382 (c) 2020 by the American Academy of Ophthalmology