Epitope analysis of MPO-ANCA in vasculitis.

Myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) has been widely detected in some diseases. It appears that the titer of MPO-ANCA is not always correlated with the activity of the disease. The epitope mapping of MPO-ANCA using recombinant proteins has been demonstrated to be effective in elucidating their etiology. The recombinant fragments of the MPO molecule have been expressed in E. coli without the association of the sugar moiety for the epitope analysis. The Western blotting and ELISA using the purified recombinant deletion mutants of human MPO has been established. It seems to be useful for sub-classifica-tion of MPO-ANCA related vasculitis. When epitope of sera of patients with MPO-ANCA-related renal diseases and vasculitis was analyzed by the Western blotting. Most of the sera reacted with either of the region of N- or C-terminus of the heavy chain, whereas no serum reacted with the light chain regions. Recently, some model mice of MPO-ANCA have been examined also.