The fruits of CD40 research in basic and clinical medicine will soon be harvested.

The CD40 ligand/CD40 pathway is widely recognized for its prominent role in immune regulation and homeostasis. CD40, a member of the tumor necrosis factor receptor family, is expressed by antigen-presenting cells, as well as non-immune cells and tumors. The engage-ment of the CD40 and CD40 ligands, which are transiently expressed on T cells and other non-immune cells under inflammatory conditions, regulates a wide spectrum of molecular and cellular processes, including the initiation and progression of cellular and humoral adaptive immunity. Based on recent research findings, the engagement of the CD40 with a deregulated amount of CD40 ligand has been implicated in a number of inflammatory diseases. We will discuss the involvement of the CD40 ligand/CD40 interaction in the pathophysiology of inflammatory diseases, including autoimmune diseases, atherothrombosis, cancer, and respira-tory diseases.