NEUTROPHIL CYTOPLASMIC ANTIBODY WITH REFLEX TO MPO/PR3 ANTIBODIES
- NEUTROPHIL CYTOPLASMIC ANTIBODY WITH REFLEX TO MPO/PR3 ANTIBODIES
- Start Date
- Expiration Date
- Anti-Neutrophil Cytoplasmic Antibody Evaluation; ANCA Antibody Evaluation
- CPT Codes
- 86255, If reflexed, add 83516 x 2
- Reference Test
- Transport Info
Refrigerated 48 Hours
If specimen will not be received within 48 hours of collection, freeze serum and transport frozen
- Fasting Required?
- Patient Instructions
- Reference Range
Qualitative (screening): Negative for the presence of ANCA (Anti-Neutrophil Cytoplasmic Antibodies)
Semi-Quantitative (titer): - Less than 1:20 = not significant
Interpretation of Results for MPO and PR-3 IgG:
Negative: Less than or equal to 20 Index Value
Weak Positive: 21-30 Index Value
Moderate to Strong Positive: Greater than 30 Index Value
MPO/PR-3, if indicated: Enzyme-Linked Immunosorbent Assay (ELISA)
Diagnosis and follow-up of Wegener’s Granulomatosis (WG)
Evaluation of patients suspected of having systemic vasculitis, especially patients with renal disease or unexplained multi-organ disease possibly due to vasculitis
Anti-neutrophil cytoplasmic antibodies (ANCA) are autoantibodies specific for neutrophil lysosomal enzymes, particularly for proteinase-3 (PR-3, a serine proteinase) and myeloperoxidase (MPO). Cross-reaction has also been seen with cationic protein 57 (CAP 57), cathepsin G, elastase, lactoferrin, and other lysosomal proteins.Three major fluorescence patterns, perinuclear (p-ANCA), cytoplasmic (c-ANCA) and atypical (a-ANCA), are distinguished on ethanol-fixated neutrophils and confirmed by formalin-fixed neutrophils and Hep-2 cells.
The c-ANCA (cytoplasmic) pattern:The classic ANCA pattern appears as a diffuse granular cytoplasmic fluorescence and is specific for antibodies vs. serine proteinase-3 (PR-3). This pattern, characteristic of Wegener’s granulomatosis and to a lesser extent microscopic polyarteritis, has been designated c-ANCA. Patients with active generalized Wegener’s granulomatosis (WG) have a frequency of positive c-ANCA results (sensitivity) that is approximately 85-90%. A negative test of c-ANCA does not completely rule out WG. Positive c-ANCA results and antibodies to PR-3 can also be seen in polyarteritis nodosa. In patients with documented WG, rising titers of c-ANCA suggest relapse and falling titers suggest response to therapy.
The p-ANCA (perinuclear) pattern: The second ANCA pattern has been described as appearing as a perinuclear neutrophilic stain and has been designated p-ANCA. This pattern is specific for other neutrophilic enzymes, including myeloperoxidase (MPO), elastase, and lactoferrin. The most common target antigen associated with p-ANCA is MPO. p-ANCA is seen in association with a more organ-limited vasculitis, in particular pauci-immune necrotizing glomerulonephritis. p-ANCA is typically not seen in systemic vasculitis. In patients with active renal disease, a positive p-ANCA result suggests the presence of antibodies to MPO and pauci-immune necrotizing glomerulonephritis. However, positive p-ANCA results are not specific for MPO antibodies. Positive ANCA results (p-ANCA and, rarely, c-ANCA) may occur in patients with diseases other than WG or vasculitis, including Goodpasture’s syndrome, lupus erythematosus, rheumatoid arthritis, and Sjogren’s Syndrome.
The a-ANCA (atypical) pattern: This third type of ANCA pattern occurs when the initially positive p-ANCA cannot be confirmed by use of formalin-fixed slides and the ANA test is negative. This pattern has been observed in patients with ulcerative colitis and ascending cholangitis.