###### Abstract  
Background: Little is known about the relevance of BP180 ELISA for the clinical management of oral mucous membrane pemphbigoid (OMMP). The aim of the present study was to investigate if the levels of anti-BP180 antibodies at diagnosis could be correlated with clinical severity and relapse. Methods: The present study included 44 OMMP patients with positive direct immunofluorescence (DIF). Circulating anti-BP180 IgG was measured using the same available ELISA kit (Euroimmune cut-off 20 U/mL). Clinical severity at diagnosis was measured using the oral disease severity score (ODSS). Only patients who achieved clinical remission (CR) were included in the analysis of variables related to relapse. Relapse was calculated as the interval between the date of the best type of clinical remission achieved and the date of relapse. Results: Values of BP180 \(>\) 20 U/mL significantly correlated with higher ODSSs in both univariate (_p_ < 0.05) and multivariate analyses (_p_ < 0.05). Among 39/44 patients who achieved CR, 17/39 relapsed. Kaplan-Meier analysis revealed that patients with BP180 \(>\) 20 U/mL displayed worse clinical behavior in terms of relapse (_p_ < 0.05). Conclusion: BP180 ELISA at diagnosis appears to be a useful parameter to stratify OMMP patients with more severe disease and worse clinical outcomes after clinical remission. Article  
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rotein of the plakin family and represents the main target antigen of OMMP. [PERSON] et al., using immunoblotting, found that 63 of 124 studied patients with MMP (51%) showed reactivity to BP180 (including its soluble ectodomains, 120-kDa LAD-1 and 97-kDa LABD97 antigens) [4]. [PERSON] et al., using Western blotting analysis with the combined use of the soluble BP180 ectodomain (LAD-1) and recombinant BP180 NC16A, found that 16 of the 19 MMP patients' sera (84%) targeted BP180 [5]. More specifically for OMMP, [PERSON] et al. found that 56% of OMMP patients reacted to BP180 using a combination of indirect immunofluorescence with 1 M NaCl-split skin, immunoblot analysis, and ELISA [3]. ELISA testing for circulating autoantibodies detection is an easy-to-perform, moderately expensive, and minimally invasive serological technique that has emerged as an optimal diagnostic biomarker for BP with excellent values of sensitivity and specificity [6]. By contrast, in MMP, the titer of circulating pathogenic antibodies is well known to be lower than in BP, thus limiting the diagnostic utility of ELISA techniques for the diagnosis of OMMP [7]. Indeed, [PERSON] et al., evaluating BP180 NC16A ELISA in OMMP, found a sensitivity of only 50% (using commercially available MBL Kit cut-off 9 U/mL) [8]. However, in the same study, the authors also found a linear correlation between the titer of BP180 and oral disease severity score (ODSS). Other studies failed to demonstrate an association between BP180 and greater clinical severity. [PERSON] et al., analyzing the profiles of 78 patients with MMP by means of indirect immunofluorescence (IIF), immunoblotting (IB), and ELISA, found that BP180 reactivity was inversely correlated with disease severity [9]. Similarly, [PERSON] et al., analyzing 22 MMP patients by means of ELISA, found that BP180 NC16a reactivity was associated with the low-risk clinical phenotype but referred to patients characterized by only oral mucosal lesions or combined oral mucosal and skin lesions and not involving the eyes, upper respiratory tract, or esophagus [10]. Despite the fact that it is to be expected that high levels of this protein might influence the outcome of the disease, like in Pemphigus Vulgaris, another autoimmune blistering disease of the oral cavity [11; 12], there is not enough evidence that BP180 levels can predict disease severity and prognosis in OMMP. Conflicting results may depend on several factors such as the sample size, the different techniques or kits used for BP180 analysis, or differences among clinical phenotypes involving different sites.