Buku Medicine

ANA & related

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Anti-neuronal

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Vasculitis/ANCA

Two patterns:

  1. C-ANCA [mostly granulomatosis with polyangiitis aka GPA (formerly Wegener’s granulomatosis); 90% of which are ANCA+]. Due to antibodies against Proteinase-3
  2. P-ANCA [some GPA, microscopic polyangiitis, eosinophilic GPA (formerly Churg-Strauss), glomerulonephritis, sclerosing cholangitis, autoimmune hepatitis, ulcerative colitis]. Due to antibodies against myeloperoxidase, lactoferrin, cathepsin, elastase.

In GPA, the monitoring titre of ANCA is useful: rising titre in a patient in clinical remission heralds relapse.

ANCA may appear as a consequence of chronic neutrophil activation and turnover (e.g. cystic fibrosis, bronchiectasis)

 

 

 

 

Liver

Quick tip: Autoimmune hepatitis prognosis is dependent upon type and early diagnosis.

Autoimmune hepatitis

  • Antibodies to HCV or HCV PCR+ = exclusion criteria for autoimmune hepatitis.
  • Autoimmune hepatitis Type 1 [AIH-1]
    • ANA+, smooth muscle Ab [SMA]+, P-ANCA+, and soluble liver antigen [SLA] Ab+.
    • Patients may be positive to both ANA/SMA, whereas others will have positivity of only one antibody and others may be antibody negative (but biopsy-proven).
    • Typically occurs in adults and has a better prognosis and responds well to therapy.
  • Autoimmune hepatitis Type 2 [AIH-2]
    • Typically liver-kidney microsomal [LKM-1, LKM-3] Ab+ and liver cytosol [LC-1] Ab+.
    • AIH-2 is seen in children and has a worse prognosis with poor response to therapy.

Prognosis is dependent on type and early diagnosis

  • Liver-kidney microsomal antibodies are also associated with drug-induced hepatitis [espec. halothane] and chronic hepatitis C or D.
  • Non-actin smooth muscle antibodies may be seen in SLE and after viral infections.

Primary Biliary Cirrhosis

  • 95% positive for anti-mitochondrial antibodies [anti-M2]. Remainder may have antibodies against S100 antigen of nuclear membrane [Nsp-II pattern] or gp210, another nuclear antigen. Type of antibody present has no influence on prognosis or response to therapy.
  • Marked elevation in IgM

Skin

Quick tip: the corresponding serum antibodies can be negative in the presence of these conditions. Biopsy is often required.

Bullous pemphigoid

  • Antibodies bind to dermal-epidermal junction and recognise hemidesmosome antigens [BP 230 and BP 180].
  • Detected by direct immunofluorescence on skin biopsies or in serum [only 70% of patients have detectable circulating antibodies].
  • Herpes gestationis (bullous disease in pregnancy)
  • Antibodies to BP 180 binding to dermal-epidermal junction on direct immunofluorescence of biopsies, often negative for serum antibodies.

Pemphigus

  • Antibody binds to cell surface of stratified squamous epithelium, recognises desmosomal protein desmoglein.
  • 80-90% of patients have detectable antibody in serum.

Urticarial vasculitis

  • May be associated with auto-antibodies to C1q (these may also be seen in SLE and have been said to correlate with renal disease).
  • Urticarial vasculitis typically causes prolonged urticarial lesions (>24 hours) that fade with bruising. Biopsy confirms vasculitis.