Serum levels of immunoglobulins G1 and G4 targeting the non-collagenous 16A domain of BP180 reflect bullous pemphigoid activity and predict bad prognosis.

Bullous pemphigoid (BP) is an autoimmune subepidermal bullous disease, and different immunoglobulin (Ig)G autoantibody subclasses may play different roles in the pathogenesis of BP. This study aims to evaluate the relationship between specific IgG subclasses and BP. Enzyme-linked immunoassays (ELISA) were developed to test the IgG subclasses targeting the non-collagenous 16A (NC16A) domain of BP180. A statistical analysis was carried out to assess the relationship of BP and IgG subclasses as well as other factors. The correlation coefficients between the ELISA scores for four IgG subclasses and disease severity scores were 0.586 for IgG, 0.441 for IgG1, 0.594 for IgG2, 0.345 for IgG3, and 0.448 for IgG4 before treatment. After treatment, the correlation coefficient was 0.376 for IgG, 0.522 for IgG1, 0.314 for IgG2, 0.582 for IgG3 and 0.503 for IgG4. Spearman's rank correlation coefficient was 0.801 for IgG1, 0.66 for IgG2, 0.575 for IgG3 and 0.463 for IgG4 between the ELISA scores of IgG subclasses and the disease severity score variation. The ELISA scores of IgG subclasses in patients with mucosal involvement were higher than those without. Survival analysis showed that sex, IgG1 and IgG4 were the independent predictors for BP. In conclusion, the serum levels of IgG1 and IgG4 targeting BP180NC16A were paralleled with disease severity in BP patients. IgG1 and IgG4 and sex were the independent prognostic factors for an early prognosis of BP.