PR3 and MPO antibodies and vasculitis associations

Antibody, antigen, disease

  • 1.C-ANCA, 2.PR3 antigen, 3.Wegener, granulomatosis with polyangiitis
  • 1.P-ANCA, 2.MPO antigen, 3.microscopic polyangiitis

The pooled sensitivity and specificity of the pattern of immunofluorescent staining (c-ANCA vs p-ANCA) for ANCA-associated vasculitides are 66% and 98%, respectively. However, when there is concordance between the immunofluorescent staining pattern and the target antigen (eg, when a c-ANCA pattern is associated with antibodies against PR3 and when a p-ANCA pattern is associated with antibodies against MPO), the diagnostic accuracy of serologic testing for GPA and MPA, respectively, is higher. Conversely, when there is discordance (eg, c-ANCA is not associated with PR3 positivity), then the uncertainty remains high.