CD40LG and systemic lupus erythematosus: The 2006 revised classification criteria for definite APS are met when at least one clinical criterion (vascular thrombosis or pregnancy morbidity), and one biological criterion (Lupus Anticoagulant [LAC], IgM/IgG anti-cardiolipin [aCL], and/or IgM/IgG anti-2GPI positivity) are present.