Importance:A rare variant of mucous membrane pemphigoid (MMP) is characterized by circulating antilaminin 332 (Lam332) autoantibodies and seems to be associated with concurrent malignant neoplasms.Objective: To determine the prevalence and clinical significance of anti-Lam332 autoantibody detection from a large series of patients with MMP.Design: Multicenter retrospective study. Interventions: Serum samples were analyzed by a new Lam332 enzyme-linked immunosorbent assay (ELISA); clinical and immunopathologic data were obtained from the patients' medical records.
Main Outcome Measures:The Lam332 ELISA scores were evaluated with respect to clinical characteristics, standard and salt-split indirect immunofluorescence, and bullous pemphigoid (BP) 230 and BP180-NC16A ELISAs.Results: The Lam332 ELISA score was positive (Ն9 U/mL) in 20.1% of serum samples from patients with MMP, 1 of 50 patients with bullous pemphigoid (BP), none of 7 with pemphigus, and 3 of 32 other controls. No relationship was evidenced between a positive ELISA Lam332 score and age; sex ratio; oral, ocular, genital, skin, or esophageal/laryngeal involvement; internal malignant neoplasm; or BP180 ELISA score. Salt-split skin indirect immunofluorescence and ELISA BP230 results were more frequently positive when Lam332 ELISA results were positive (P=.04 and .02, respectively). Patients with a positive Lam332 ELISA score frequently had more severe MMP (67.8% vs 47.2%; P=.04).
Conclusions and Relevance:Results of this novel ELISA showed that serum anti-Lam332 autoantibodies are detected in 20.1% of patients with MMP. AntiLam332 autoantibodies are mainly detected in patients with severe MMP but not preferentially in those with a malignant neoplasm. The association between antiLam332 and anti-BP230 autoantibodies might arise from an epitope-spreading phenomenon.