Figure 2: CD40L:CD40 and APCs. Activation of CD40 on APCs results in enhanced survival of DCs and monocytes and secretion of IL-1α, IL-6, IL-8, IL-10, IL-12 and TNF-α from the corresponding APCs. It also induces maturation of dendritic cells (DCs). CD40L-CD40 alters the phenotype of DCs by upregulating expression of costimulatory molecules including CD54/ ICAM-1, CD58/LFA-3, CD80/B7-1. Increased IL-12 secretion and CD80/CD86 expression have an important impact on T cell activation.