Validation of chemiluminescent enzyme immunoassay in detection of autoantibodies in pemphigus and pemphigoid

Background A novel chemiluminescent enzyme immunoassay (CLEIA) was recently developed to quantify autoantibodies specific for desmogleins (Dsgs) and BP180, the target antigens of pemphigus and pemphigoid. This assay is automated and highly accurate and efficient. Objective To validate the use of the CLEIA for detection of autoantibodies during the clinical courses of patients with pemphigus and pemphigoid. Methods To define cut-off values for Dsg1, Dsg3, and BP180, we evaluated 47 serum samples from patients with pemphigus foliaceus (PF), 59 from those with pemphigus vulgaris (PV), 52 from those with bullous pemphigoid (BP), and 995 from healthy individuals. We also evaluated any fluctuations in CLEIA titers according to disease activity during the clinical course of 10 cases each of PF, PV, and BP. We used clinical symptom scores, the pemphigus disease area index (PDAI) and the bullous pemphigoid disease area index (BPDAI), to evaluate disease activity. Results The cut-off values for the CLEIA titers determined by the Youden index were 15.4 U/mL for Dsg1, 14.9 U/mL for Dsg3, and 16.8 U/mL for BP180. CLEIA titers fluctuated in parallel with the PDAI/BPDAI scores in 28 of the 30 cases with PF, PV, or BP. Although the CLEIA and enzyme-linked immunosorbent assay (ELISA) values in the same samples differed substantially in some cases, the concordance rates of positive/negative results between the CLEIA and ELISA were 96% for Dsg1, 97% for Dsg3, and 96% for BP180. Conclusion The CLEIA, a newly developed, highly effective autoantibody detection system, is as reliable as ELISA for evaluation of the clinical courses of pemphigus and pemphigoid.