Correlation of <scp>BP180</scp>, <scp>BP230</scp>, and type <scp>VII</scp> collagen antibody titers in serum, blister fluid, erosion, and saliva in pemphigoid diseases

Autoantibodies, including anti-BP180 and anti-BP230 antibodies in bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP), and anti-type VII collagen (COL7) antibodies in epidermolysis bullosa acquisita (EBA), are well characterized. Enzyme-linked immunosorbent assays (ELISAs) for the detection of these antibodies in the serum are valuable for diagnosis. Previous studies have indicated that anti-BP180 and anti-BP230 antibodies in blister fluid and saliva can be detected using ELISA. The aim of this study was to detect anti-BP180, anti-BP230, and anti-COL7 antibodies in several types of samples, including blister fluid, an erosive surface swab, and saliva, by ELISAs and to compare the titers of these antibodies between different types of samples. Thirty-three patients with BP/MMP, two patients with EBA, and 13 patients with non-pemphigoid diseases were included in this study. Samples were collected from each patient and analyzed using commercial ELISA kits. In the cases of BP/MMP, the mean ± standard deviation indices of BP180 ELISA were 411.9 ± 538.3, 253.5 ± 333.3, 2.360 ± 1.714, and 1.599 ± 1.262, and those of BP230 ELISA were 27.73 ± 37.65, 20.52 ± 30.04, 0.486 ± 0.7915, and 0.346 ± 0.4373, from sera, blister fluids, erosive surface swabs, and saliva, respectively. The indices of BP180 and BP230 ELISAs using serum were significantly correlated with those of BP180 and BP230 ELISAs using blister fluid (r = 0.9342 and r = 0.9882), an erosive surface swab (r = 0.7586 and r = 0.9332), and saliva (r = 0.5731 and r = 0.6147), respectively. This study revealed that autoantibodies were detectable in blister fluids, erosive surfaces, and saliva, and their correlation with serum titers in pemphigoid diseases was highest in blister fluid. In summary, blister fluid can be a minimally invasive sample alternative to serum for the detection of pemphigoid-related antibodies.