Rheum: Antibodies

Question 1

SLE

a) Most specific
b) Also positive
c) Drug-induced lupus

Answer 1

a) Anti-Smith (Sm) - but only 30% sensitive
- Anti dsDNA - around 70% sensitive

b) Anti-nuclear antibody (ANA) - 95% sensitive; not specific
- RhF, Anti-cardiolipin

c) Anti-histone

Question 2

Sjogrens

a) Most specific
b) Also positive

Answer 2

a) Anti-Ro,

b) Anti-La

Question 3

Myositis (poly/dermato)

- also give signs of dermatomyositis

Answer 3

Anti-Jo-1

• Macular rash, gottron papules and heliotrope rash

Question 4

Scleroderma

a) Limited cutaneous (CREST)
b) Diffuse cutaneous
c) Present in most but non-specific

Answer 4

a) Anti-centromere

b) - Anti-topoisomerase (Anti-Scl-70)
- Anti-RNA polymerase III

c) ANA

Question 5

Anti-mitochondrial antibody

Answer 5

PBC

Question 6

Goodpastures

Answer 6

Anti-GBM

Question 7

Wegener’s (GPA)

Answer 7

c-ANCA

Question 8

Churg-Strauss

Answer 8

p-ANCA

Question 9

PBC vs PSC

a) Antibodies
b) Clinical features
c) Risk factors
d) Management

Answer 9

a) - PBC - Anti-mitochondrial antibody (AMA)
- PSC - p-ANCA

b) Itching, fatigue
- PBC more commonly asymptomatic, associated with liver cirrhosis and liver Ca (intrahepatic)
- PSC more commonly aggressive, associated with cirrhosis and cholangiocarcinoma (extrahepatic)

c) PBC - women, RA;
PSC - men, IBD

d) Itch - cholestyramine;
PBC - UDCA
PSC - transplant liver

Question 10

Antiphospholipid syndrome

Answer 10

Anti-cardiolipin

Lupus anticoagulant

Question 11

Rheumatoid arthritis

a) 2 main antibodies
b) If both positive - indicates…?
c) If both are negative - indicates…?

Answer 11

a) - RhF (sensitive; non-specific - 5% normal pop.)
- Anti-CCP (specific)

b) If both positive - worse prognosis/ more aggressive
c) If both negative - seronegative arthritis (may be seronegative RA or seronegative SpA, etc.)

Question 12

MG.

Answer 12

Anti-ACh (on post-synaptic membrane of NMJ)

Question 13

Anti-nuclear antibody.

a) Present in what % normal population
b) Is it sensitive or specific for CTD?
c) Diseases it is commonly positive in

Answer 13

a) 5% normal population
b) Sensitive (not specific) - good at ruling IN people with the disease but not ruling out people without disease

c) SLE
- Other CTD (eg. scleroderma)
- Polymyositis/ dermatomyositis
- JIA
- Autoimmune hepatitis

Question 14

Autoimmune hepatitis

Answer 14

ANA

Anti-smooth muscle antibody (Anti-SMA)

Question 15

ANCA.

a) What are they?
b) c-ANCA - target protein
c) p-ANCA - target protein
d) Associated conditions

Answer 15

a) Autoantibodies directed against antigens found in the cytoplasmic granules of neutrophils and monocytes

b) c-ANCA:
- targets a protein called PR3 (proteinase 3)

c) p-ANCA:
- targets a protein called MPO (myeloperoxidase)

d) - Vasculitis: GPA (more c-ANCA), Churg-Strauss (more p-ANCA), polyarteritis nodosa
- PSC
- IBD, other autoimmune disease, infection, etc.