Antineutrophil cytoplasmic antibodies and associated diseases: A review ofthe clinical and laboratory features

There have been a number of recent advances in this held. First. the "Inter national Consensus Statement on Testing and Reporting of Antineutrophil Cyt oplasmic Antibodies (ANCA)" has been developed to optimize ANCA testing. It requires that all sera are tested by indirect immunofluorescent (IIF) exam ination of normal peripheral blood neutrophils and, where there is positive fluorescence, in enzyme-linked immunosorbent assays (ELISAs) for antibodie s against both proteinase 3 (PR3) and myeloperoxidase (MPO). Testing will b e further improved when international standards and common ELISA units are available. Second, new diagnostic criteria for the small vessel vasculitide s that take into account ANCA-positivity and target antigen specificity as well as histologic features are currently being produced. Third, we underst and that the complications associated with treatment of the ANCA-associated vasculitides are often more hazardous than the underlying disease. and reg imens that use effective but less toxic agents are being evaluated. The fac tors associated with increased risk of relapse, however, remain incompletel y understood. Finally. ANCA with specificities other than PR3 and MPO are p resent in many nonvasculitic autoimmune diseases. Their clinical significan ce is still largely unclear, and some of the target antigens are present in other cells as well as neutrophils and thus are not strictly "ANCA."