Autoantibodies

Question 1

RF

Answer 1

• Autoantibody to Fc of IgG
• RA 80% | SSc 50% | SLE 25%
• Sensitive, not specific (eg. IE, Hep C, TB)

Question 2

Anti-CCP

Answer 2

Specific for RA >95%

Question 3

ANAs

Answer 3

• Ab against nuclear components (DNA/RNA/histones/centromeres)
• SLE 98% | MCTD 100%
• SSc 70% | LC SSc 80%
• Sensitive, not specific in CTD. Low titres may be seen in normal controls

Question 4

Anti-DS DNA

Answer 4

Sensitive SLE 70%

SPECIFIC FOR SLE = 95%

Question 5

Anti-Smith (Anti-SM)

Answer 5

Highly specific for SLE

Not sensitive ~ 30%

Question 6

Anti-Ro/Anti-La (SSA/SSB)

Answer 6

Seen in SSc
In ANA negative SLE –> can be +ve
Anti-Ro associated with neonatal lupus + CHB

Question 7

Antiphospholipid (B2 micro/lupus anticoag/anti-cardiolipin)

Answer 7

Diagnostic of APLS

Question 8

Anti-histone

Answer 8

95% of drug induced lupus

• hydralazine/minocycline/isoniazid
• quinidine/procainamide
• TNF blockade
• SSZ | anti-epileptics

Question 9

Anti-U1 RNP

Answer 9

Unique to MTCD

Overlap feature syndrome of SLE, SSc,myositis and RA

Question 10

Anti-centromere

Answer 10

Specific for limited cutaneous SSc

Question 11

Anti-topoisomerase I (anti-Scl 70)

Answer 11

Specific for Diffuse SSc

Suggestive of pulmonary fibrosis risk

Question 12

Anti-RNA polymerase III

Answer 12

Suggestive of SSc Renal crisis risk

Question 13

Anti-tRNA synthetase (Anti-Jo1)

Answer 13

Anti-synthetase Syndrome

• Acute constitutional symptoms
• Myositis
• Raynaud’s + Mechanic hands
• Non-erosive arthritis
• ILD

Question 14

Anti-MDA5

Answer 14

Amyopathic DM + ILD risk

Treat with tofacitinib

Question 15

Anti-SRP (signal recognition protein)

Answer 15

Necrotising myositis

Question 16

Anti-Mi2

Answer 16

Specific not sensitive for idiopathic inflammatory myositis