Which antibody in SLE is MOST strongly associated with secondary anti-phospholipid syndrome (APS) and recurrent arterial thrombosis?
- A Anti-dsDNA antibody
- B Anti-Sm antibody
- C Lupus anticoagulant (LA) ✓
- D Anti-histone antibody
Explanation
Lupus anticoagulant (LA) is paradoxically named—it prolongs the APTT in vitro but causes thrombosis in vivo by binding phospholipid-protein complexes (especially beta-2 glycoprotein I). Among the three main antiphospholipid antibodies (LA, anti-cardiolipin, anti-β2-GPI), lupus anticoagulant carries the highest thrombotic risk and is the strongest predictor of APS-related events including stroke, DVT, recurrent miscarriage, and thrombocytopenia. Anti-dsDNA and anti-Sm are highly specific for SLE but do not directly mediate thrombosis. Anti-histone is seen in drug-induced lupus.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.