Final answer:
IL-2, produced by helper T (TH) cells, specifically activates cytotoxic T (TC) cells to transform into cytotoxic T lymphocytes (CTLs), which are pivotal in controlling and eliminating intracellular pathogens by destroying infected cells.
Step-by-step explanation:
The cytokine Interleukin-2 (IL-2), produced by helper T (TH) cells, plays a pivotal role in the immune response by activating various cells of the immune system. After being secreted by TH cells, IL-2 particularly activates cytotoxic T (TC) cells to transform into cytotoxic T lymphocytes (CTLs). CTLs are essential for targeting and killing infected cells, thereby playing a critical role in controlling and eliminating intracellular pathogens.
The activation of TC cells by IL-2 to become CTLs is crucial for the cell-mediated immune response, which seeks to eradicate cells infected by viruses or transformed by cancer. Through this process, CTLs can effectively target and destroy cells that display antigens on their surface via Major Histocompatibility Complex class I (MHC I) proteins, a hallmark of infected or abnormal cells. This specific function distinguishes TC cells as a central component of the adaptive immune response.
IL-2 does not directly activate antigen-presenting cells (APCs), macrophages, induce phagocytosis, or mature additional TH cells. These functionalities are typically influenced by other cytokines and interactions within the immune system.