Final answer:
Cytotoxic T cells (CD8+) are immune cells that target and destroy infected host cells, primarily through inducing apoptosis. They become activated upon recognizing antigens presented by MHC I molecules and are vital in the swift adaptive immune response to viral infections.
Step-by-step explanation:
Cytotoxic T cells (Tc) are a critical component of the adaptive immune system and play a vital role in defending the body against viruses and other intracellular pathogens. These cells carry out their function by recognizing and binding to the infected host cells through their CD8+ receptors and MHC I molecules. Once engaged, they induce apoptosis or cell death in these targets. Tc cells utilize molecules such as Fas ligand or perforin and granzymes to execute this process effectively. Crucially, TC cells also form memory cells to provide a faster response upon subsequent exposure to the same pathogen.
Cytotoxic T cells become activated when naïve CD8+ T cells engage with antigen-presenting cells (APCs) that present an antigen in the context of MHC I. Following recognition and interaction, these T cells undergo a process of clonal expansion and differentiation into effector cytotoxic T cells or memory T cells. This enables the immune system to respond robustly to infections, particularly viral ones, that are known to hide within host cells to evade immune detection.