CD40LG and acute promyelocytic leukemia: APS is defined by pregnancy morbidity (mainly fetal losses) and thromboses (arterial and/or venous) in association with the presence of at least one APL AAb [lupus anticoagulant, anticardiolipin (IgM or IgG), and anti-β2 glycoprotein I (IgM or IgG) AAb] on two or more occasions at least 12 weeks apart (111).