CD4-positive helper T lymphocyte (CD4+ T cell)

CD4-positive helper T lymphocytes are a principal subset of T cells critical for the proper functioning of the adaptive immune system[1][2][3]. They are identified by the presence of CD4 on their surface, which serves as a coreceptor for the major histocompatibility complex class II (MHC-II) on antigen-presenting cells. Upon activation, CD4+ T cells differentiate into specialized subtypes including Th1, Th2, Th17, Treg, and Tfh cells, each with distinct cytokine profiles and immune functions[4][6]. These cells orchestrate immune responses by stimulating B cells for antibody production, activating cytotoxic T cells and macrophages, and regulating inflammatory processes. CD4+ T cell depletion, especially due to HIV infection, leads to severe immunodeficiency, making their enumeration and preservation a key focus in infectious disease therapy and monitoring[2][7]. Their dysregulation is implicated in autoimmunity, cancer, and exacerbated inflammatory responses[1][4][6].

Other names

T helper lymphocyteT helper cellCD4+ T cellCD4 T lymphocyteCD4-positive T cellTh cellHelper T cell

Inhibition of viral entry or replication (ART drugs prevent HIV from infecting or destroying CD4+ T cells)[2] Suppression of immune function (immunosuppressants reduce T cell activation, cytokine production)[4] Modulation of cytokine signaling or subset differentiation (biologics target specific cytokines produced by T cell subsets)[4][6]