Anti-BP180 and anti-BP230 enzyme-linked immunosorbent assays for diagnosis and disease activity tracking of bullous pemphigoid: A prospective cohort study
Kumutnart Chanprapaph,1 Vipawee Ounsakul,1 Duangrat Pruettivorawongse,1 Kunlawat Thadanipon1,2
1 Division of Dermatology, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
2 Section for Clinical Epidemiology and Biostatistics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
Abstract
Background: Autoantibodies against BP180 and BP230 play major roles in bullous pemphigoid (BP). We are the first to describe the values of serum anti-BP180 IgG and anti-BP230 IgG enzyme-linked immunosorbent assays (ELISA) for diagnosis and disease monitoring of BP among Thai patients.
Objectives: We aimed to determine the diagnostic performance of anti-BP180 IgG and anti-BP230 IgG in BP, to correlate disease activity with autoantibody levels through follow-ups, and to relate BP comorbidities with disease activity and autoantibody levels.
Methods: Consecutive patients suspected of having BP were included. Skin biopsy, direct immunofluorescence, and serum anti-BP180 IgG and anti-BP230 IgG tests were performed. BP disease area index (BPDAI) was evaluated at diagnosis and throughout follow-ups.
Results: Of 131 patients, 68 were diagnosed with BP, and 63 were included as controls. Sensitivity and specificity of serum anti-BP180 IgG were 69.1% and 90.5%, respectively, while those of serum anti-BP230 IgG were 55.9% and 85.5%, respectively. Using anti-BP180 and anti-BP230 IgG antibodies resulted in a 7% increase in sensitivity compared with using anti-BP180 IgG antibody alone. Significant correlation with BPDAI was found for both autoantibodies at diagnosis but only for anti-BP180 IgG at follow-ups (p = 0.013). BP patients with positivity to anti-BP180 or anti-BP230 IgG had significantly higher BPDAI than did those without (p = 0.005). BP was associated with neurological diseases (p = 0.025), while patients with diabetes had higher disease activity (p = 0.010).
Conclusions: While both serum autoantibodies are useful for diagnosing BP in patients with suspicious clinical features, only anti-BP180 IgG allowed prediction of disease activity over time.
Key words: anti-BP180 ELISA, anti-BP230 ELISA, bullous pemphigoid, BPAG1, BPAG2