T helper cell (CD4+ T cell) (CD4+ T cell (also known as Th cell))

CD4+ T cells (helper T cells) are a key lymphocyte subset expressing the CD4 surface protein, central to orchestrating the adaptive immune response. They function primarily by secreting cytokines that activate and regulate other immune cells, including B cells, cytotoxic T cells, macrophages, and neutrophils. Measurement of CD4+ cell count is a critical biomarker for immune competence, especially in HIV infection, where viral depletion of CD4+ cells results in immunodeficiency and increased susceptibility to opportunistic infections. Therapeutic interventions may target, preserve, or modulate CD4+ T cells to restore or suppress immune responses in HIV/AIDS, autoimmune disorders, and transplantation

Other names

helper T cellCD4-positive lymphocyteCD4+ lymphocyteTh cellT4 cell

Increase: Drug-induced expansion/protection of CD4+ T cells (e.g., antiretrovirals block HIV replication, preserve CD4+) Decrease: Immunosuppression via cytotoxic agents, corticosteroid inhibition, HIV-induced lysis