CD40Ligand

CD40 Ligand, also known as CD154, is a protein that plays a crucial role in the immune system. It is a type II transmembrane protein, meaning it spans the cell membrane once with its amino terminus facing the cytoplasm. CD40 Ligand is primarily expressed on activated T cells, but can also be found on other immune cells like basophils, mast cells, and activated B cells.

The primary function of CD40 Ligand is to interact with its receptor, CD40, which is expressed on a variety of cells including B cells, dendritic cells, macrophages, and endothelial cells. This interaction is vital for T cell-dependent B cell activation, differentiation, and antibody production. It is essential for the development of germinal centers in lymphoid tissues, which are critical for generating high-affinity antibodies and immunological memory.

Beyond its role in B cell regulation, CD40 Ligand signaling also influences the maturation and function of dendritic cells, enhancing their ability to present antigens to T cells. This interaction can promote the development of cellular immunity. Furthermore, CD40 Ligand signaling on macrophages can enhance their phagocytic activity and inflammatory responses. Dysregulation of CD40 Ligand has been implicated in various autoimmune diseases and immunodeficiencies. Antibodies targeting CD40 Ligand have been developed as therapeutic agents for conditions such as rheumatoid arthritis and lupus.