Increased sensitivity and high specificity of indirect immunofluorescence in detecting IgG subclasses for diagnosis of bullous pemphigoid

Summary

Background

Indirect immunofluorescence (IIF) microscopy on monkey oesophagus is an important assay for the diagnosis of bullous pemphigoid (BP). Its relatively low sensitivity (60–80%) may be partly due to insufficient detection of minor IgG subclasses.

Aim

To determine the operating characteristics of an IgG subclass in IIF.

Methods

We designed a retrospective, dual-centre, controlled cohort study on sera from 64 BP sera that had been rated as false negatives by traditional IIF microscopy, and assessed circulating IgG₁, IgG₃ and IgG₄ autoantibodies.

Results

The sensitivities of IIF in detecting IgG₁, IgG₃, IgG₄ and all three in combination were 45.3%, 18.8%, 32.8% and 48.4%, respectively. Specificities were > 97%.

Conclusion

Detection of IgG subclass (especially IgG₁ and IgG₄) autoantibodies by IIF on monkey oesophagus can significantly improve diagnostic performance of IIF microscopy for diagnosis of BP.