CD40LG and Autoimmunity: Since autoimmune patients have elevated serum levels of soluble CD40L, treatment with Fc-domain intact anti-CD40L could form immune complexes consisting of soluble CD40L and anti-CD40L antibodies, which then activate platelets in an FcγRIIa (CD32)-dependent manner and trigger thromboembolic events (Langer et al., 2005; Robles-Carrillo et al., 2010).