CD4+ T-helper cells (Th) are the white blood lymphocytes expressing surface glycoprotein antigen CD4. These T-helper cells play an important role in the adaptive immune system by releasing T cell cytokines that help other immune cells to suppress or regulate immune responses. CD4+ T-helper lymphocytes can be divided into two types (Th1 and Th2) based on their cytokine secretion. Th1 cells are involved in cell-mediated immune response to intracellular pathogens and delayed-type hypersensitivity reactions.
