Myeloperoxidase binds to vascular endothelial cells, is recognized by ANCA and can enhance complement dependent cytotoxicity.

Myeloperoxidase (MPO) and proteinase-3 (Pr-3) can bind to vascular endothelial cells (EC) and are available for recognition by autoantibodies present in P-ANCA or C-ANCA containing sera, respectively. The bound MPO also retains its enzymic functions and effectively interacts with hydrogen peroxide to mediate detachment of endothelial cells from their substratum. EC bound MPO-anti-MPO complexes can contribute to the complement-dependent EC injury demonstrated by some P-ANCA sera.