Anti-Neutrophil Cytoplasm Autoantibodies (ANCA). The Need for Specific and Sensitive Assays

Abstract

Anti-neutrophil cytoplasm antibodies (ANCA) are a group of autoantibodies primarily associated with systemic vasculitis. Hitherto, the method of choice for ANCA detection has been indirect immunofluorescence (IIF). By this method two major patterns can be seen: a cytoplasmic pattern (cANCA) or a perinuclear pattern (pANCA). The cANCA pattern is most often caused by antibodies directed against proteinase-3 (PR3) and in rare cases it is caused by anti-myeloperoixdase (MPO) antibodies. The pANCA pattern can de caused by antibodies directed against a large group of proteins i.e. MPO, lactoferrin and bactericidal/permeability-increasing protein. Often there is a discrepancy between the results obtained by IIF and those reported from the use of assays with purified antigens. This causes confusion. Until now only anti-PR3 and anti-MPO have been found of any clinical value. Therefore, it would be more proper to use assays with these highly purified antigens instead of an unspecific method like IIF.

Key Words:

• proteinase-3
• myeloperoxidase
• ANCA
• methodology