@article {Galperin416, author = {Claudio Galperin and Gary S. Hoffman}, title = {Antineutrophil cytoplasmic antibodies in Wegener{\textquoteright}s granulomatosis and other diseases: clinical issues}, volume = {61}, number = {6}, pages = {416--427}, year = {1994}, publisher = {Cleveland Clinic Journal of Medicine}, abstract = {BACKGROUND An association between antineutrophil cytoplasmic antibodies (ANCA) and nonimmune complex-mediated glomerulonephritis was first reported over 10 years ago. In Wegener{\textquoteright}s granulomatosis, the antibody usually binds proteinase 3. Antibodies to a variety of other antigens have been identified in a broad range of diseases.SUMMARY The typical coarse, granular cytoplasmic ANCA pattern on indirect immunofluorescence almost always indicates reactivity with proteinase 3, whereas the perinuclear ANCA pattern may reflect reactivity with a host of different antigens. Antibodies to proteinase 3 are overwhelmingly associated with Wegener{\textquoteright}s granulomatosis (specificity \> 90\%). In a significant number of patients, however, disease activity is not linked to an ANCA titer. ANCA may play a role in the pathogenesis of many types of inflammatory conditions. Antibodies to proteinase 3 may be important in predisposing to Wegener{\textquoteright}s granulomatosis, but definitive in vivo proof of their role is not yet available.KEY POINTS The presence of cytoplasmic ANCA in a patient who is suspected to have Wegener{\textquoteright}s granulomatosis is strong circumstantial evidence in support of that diagnosis. However, it does not represent absolute proof and should be viewed with skepticism if the clinical presentation is atypical. Conversely, a negative ANCA in the setting of a typical presentation should not rule out Wegener{\textquoteright}s granulomatosis. Because ANCA titers may not always vary in tandem with disease activity, the decision to modify therapy for Wegener{\textquoteright}s granulomatosis should continue to be based on clinical judgment.}, issn = {0891-1150}, URL = {https://www.ccjm.org/content/61/6/416}, eprint = {https://www.ccjm.org/content/61/6/416.full.pdf}, journal = {Cleveland Clinic Journal of Medicine} }