P-ANCA

Targets

p-ANCAs stain the perinuclear region by binding to specific targets. By far the most common p-ANCA target is myeloperoxidase (MPO), a neutrophil granule protein whose primary role in normal metabolic processes is generation of oxygen radicals.

ANCA will less commonly form against alternative antigens that may also result in a p-ANCA pattern. These include lactoferrin, elastase, and cathepsin G.

When the condition is a vasculitis, the target is usually MPO. However, the proportion of p-ANCA sera with anti-MPO antibodies has been reported to be as low as 12%.

Medical conditions

p-ANCA is associated with several medical conditions:

• It is fairly specific, but not sensitive for ulcerative colitis, so is not useful as a sole diagnostic test. When measured together with anti-saccharomyces cerevisiae antibodies (ASCA), p-ANCA has been estimated to have a specificity of 97% and a sensitivity of 48% in differentiating patients with ulcerative colitis from normal controls.
• Approximately 50% of cases of eosinophilic granulomatosis with polyangiitis
• A majority of primary sclerosing cholangitis
• Microscopic polyangiitis
• Focal necrotizing and crescentic glomerulonephritis
• Rheumatoid arthritis

References

References

1. (16 March 2006). "Harrison's rheumatology". McGraw-Hill Professional.
2. (2007). "Autoantibodies". Elsevier.
3. Mary Lee. (10 March 2009). "Basic Skills in Interpreting Laboratory Data". ASHP.
4. (2005). "Inflammatory Bowel Disease: Diagnostic and Treatment Options". Hospital Physician.
5. (2011). "How helpful are serological markers in differentiating crohn's disease from ulcerative colitis in indian asian inflammatory bowel disease patients?". Gut.
6. (1 November 2007). "Mayo Clinic Internal Medicine Concise Textbook". CRC Press.