Cluster of Differentiation 4 (CD4)

CD4 is a type I transmembrane glycoprotein expressed on T helper cells, monocytes, macrophages, and NK cells. It functions as a co-receptor for the T cell receptor (TCR) and MHC class II interaction, facilitating T cell activation and immune responses. It is also the primary receptor for HIV entry into cells and a target for immunotherapies in autoimmunity and transplantation.

Other names

T-cell surface glycoprotein CD4CD4 antigen

CD4 acts as a co-receptor to enhance T cell receptor signaling by binding to MHC class II molecules and recruiting Lck kinase to phosphorylate CD3 ITAMs. It also serves as a primary receptor for HIV entry into cells.