Additional Information

The necrotizing vasculitides, including Wegener’s granulomatosis, polyarteritis nodosa, Churg Strauss syndrome, idiopathic crescentic glomerulonephritis and “overlap” systemic vasculitis are a group of related diseases which vary considerably in their clinical presentations and consequently cause diagnostic problems. Wegener’s granulomatosis is a severe vascular disease characterized by necrotizing granulomas of the respiratory tract and focal glomerulonephritis. Early diagnosis is important as rapid immunosuppressive therapy has a major effect on renal outcome, but initial symptoms as presentation and the histological examination of biopsies are frequently non-specific.

The pANCA pattern on ethanol-fixed neutrophils shows sharply delineated perinuclear staining. Many samples submitted for ANCA testing will also be positive for antinuclear antibody, anti-dsDNA, anti-histone and other autoantibodies which can mimic the pANCA staining pattern. Patient samples positive for ANA can also be positive for pANCA.

It is obviously critical to distinguish true cANCA and pANCA staining patterns from other non-ANCA artifacts. This is achieved by using a combination of ethanol-fixed and formalin-fixed neutrophils slides, as indicated. Ethanol fixation of neutrophils results in the positively charged cytoplasmic granule proteins migrating to the negatively charged DNA of the nucleus, resulting in perinuclear pANCA staining. If neutrophils are treated with a cross-linking fixative such as formalin, then this migration is prevented and the cytoplasmic granule proteins remain in the cytoplasm and true pANCA samples show a granular cytoplasmic cANCA staining pattern on formalin fixed slides. ANA positive samples, when testing on formalin-fixed neutrophils, will be negative or show greatly reduced staining intensity. Granulocyte specific ANA samples producing a nuclear or perinuclear reaction of ethanol-fixed neutrophils will become negative when tested on formalin fixed neutrophils. Titers for both pANCA and cANCA patterns are