CD4 molecule (CD4)

The CD4 molecule is a glycoprotein expressed on the surface of helper T lymphocytes (CD4+ T cells). CD4 acts as a co-receptor with the T cell receptor (TCR) for recognizing antigens presented by major histocompatibility complex class II (MHC II) molecules on antigen-presenting cells. CD4 plays a critical role in initiating and regulating the immune response, supporting T cell activation, and facilitating interactions with other immune cells such as B cells, cytotoxic (CD8+) T cells, and macrophages[1][13][17]. Therapeutically, CD4 is targeted in HIV treatment (to block viral entry), immune modulation (e.g., monoclonal antibodies), and in certain autoimmune and cancer contexts. CD4-positive helper T lymphocyte activation describes the process by which naive CD4+ T cells become activated upon antigen recognition, requiring co-stimulatory signals and cytokines, ultimately leading to their differentiation into various effector subtypes and orchestration of adaptive immunity[1][2][3][7][13].

Other names

helper T cell antigenT4 antigenCD4+ T cell moleculeCD4 receptor

Inhibition of CD4 function (prevents HIV entry or modulates T cell response) Depletion of CD4+ T cells (in immunosuppressive therapy)