TNF Receptor Superfamily Member 5 / TNFRSF5 (CD40) Protein

Background

CD40 is a co-stimulatory protein primarily expressed on antigen-presenting cells (APCs), including B cells, dendritic cells (DCs), macrophages, and certain types of endothelial cells. This molecule plays a critical role in both innate and adaptive immune responses. It is a member of the tumor necrosis factor receptor (TNFR) superfamily, specifically classified as TNFRSF5. CD40 is essential for initiating and sustaining immune responses, particularly by interacting with its ligand, CD40L (CD154), which is predominantly expressed on activated T cells. The CD40-CD40L interaction is a central element in immune regulation, providing necessary signals for B cell activation, differentiation, and class switching during antibody responses. Furthermore, CD40 signaling influences macrophage activation, dendritic cell maturation, and cytokine production, all of which are crucial for orchestrating immune responses.