CD40 and autoimmune disease: In addition to the role in B cell-mediated humoral immunity, the CD40-CD40L pathway can also contribute to and play a crucial role in cell-mediated immunity, particularly in the progression of T cell-dependent autoimmune diseases.[17,18] Interaction between CD40 and CD40L can induce the overexpression of CD80/86 in mature dendritic cells and promote the activation of T cell subgroups involved in graft rejection.[19] Furthermore, blocking either CD40 or CD40L can have significant effects on T cell-mediated immunity, including T cell apoptosis and the development of regulatory T cells.[20]