What is Panca?

Understanding pANCA: Perinuclear Anti-Neutrophil Cytoplasmic Antibodies

pANCA (perinuclear Anti-Neutrophil Cytoplasmic Antibodies) is a specific type of autoantibody that targets neutrophil components and is an important diagnostic marker for certain autoimmune vasculitis conditions, particularly microscopic polyangiitis (MPA). 1

What is pANCA?

pANCA is one of the main types of ANCA (Anti-Neutrophil Cytoplasmic Antibodies) that can be detected in blood serum. It is characterized by:

• A perinuclear staining pattern when tested on neutrophils using indirect immunofluorescence
• Most commonly targets the enzyme myeloperoxidase (MPO) in the neutrophil granules
• Is detected through laboratory testing using immunofluorescence techniques on rodent tissues (stomach, kidney, and liver) 1

Clinical Significance of pANCA

Primary Association with Vasculitis

pANCA is primarily associated with:

• ANCA-associated vasculitides (AAV), particularly microscopic polyangiitis (MPA) 1
• Renal involvement in vasculitis, especially crescentic glomerulonephritis 2
• Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome) in 26-48% of cases 1

Other Clinical Associations

pANCA can also be found in:

• Inflammatory bowel disease, particularly ulcerative colitis 3, 4, 5
• Autoimmune hepatitis 1
• Indeterminate colitis 3
• Central nervous system vasculitis 6

Diagnostic Value

The diagnostic value of pANCA varies depending on the clinical context:

• In ANCA-associated vasculitis:

  • pANCA positivity, particularly when directed against MPO, is highly suggestive of microscopic polyangiitis 1
  • pANCA-positive patients are more likely to have peripheral neuropathy, glomerulonephritis, and purpura 1
  • pANCA-negative patients with vasculitis more commonly have myocardial, respiratory, and gastrointestinal involvement 1

• In inflammatory bowel disease:

  • Can help differentiate between ulcerative colitis and Crohn's disease 3, 4
  • May predict disease severity in ulcerative colitis 4

Laboratory Testing

Testing for pANCA involves:

1. Primary screening: Indirect immunofluorescence on composite sections of rodent tissues 1
2. Confirmation: ELISA testing to detect antibodies to specific targets, particularly myeloperoxidase (MPO) 1
3. Titer significance: In adults, a titer of 1:40 is considered significant; in children, titers of 1:20 for pANCA are clinically relevant 1

Clinical Implications

• Treatment decisions: Patients with ANCA-associated vasculitis should be categorized according to disease severity to guide treatment decisions 1
• Monitoring: In pediatric populations, pANCA titers can be useful biomarkers of disease activity and treatment response 1
• Prognosis: pANCA positivity in EGPA is associated with higher rates of relapse after treatment 1

Important Caveats

• A negative pANCA result does not rule out vasculitis 1
• pANCA can cross-react with enteric bacterial antigens, explaining its presence in inflammatory bowel disease 5
• pANCA-like staining can be caused by antinuclear antibodies (ANA), so ANA should be excluded when evaluating for pANCA 2
• pANCA titers in adults only roughly correlate with disease severity, clinical course, and treatment response 1

In conclusion, pANCA is an important serological marker primarily associated with ANCA-associated vasculitis, particularly microscopic polyangiitis, and has significant diagnostic and prognostic value when interpreted in the appropriate clinical context.