Antineutrophil cytoplasmic antibodies

Autoantibodies directly against neutrophilic antigens. The myeloperoxidase ANCA stains leukocyte perinuclear cytoplasm diffusely and is associated with Churg-Strauss syndrome, whereas the proteinase 3 ANCA stains the cytoplasm diffusely and is associated with Wegener granulomatosis. The pathogenic role of these antibodies is not conclusively proven, but in vitro they are able to elicit neutrophil granule release, and their titers may correlate with disease activity.