Final answer:
Cytotoxic T cells are the cells responsible for destroying target cells through a cytotoxic reaction, which is a form of non-phagocytic mechanism that involves perforin and granzymes to induce apoptosis in the infected cells.
Step-by-step explanation:
The cells that destroy target cells through an extracellular non-phagocytic mechanism referred to as a cytotoxic reaction are cytotoxic T cells. These effector cells of cellular immunity specifically target and eliminate cells infected with intracellular pathogens through induction of apoptosis. Cytotoxic T cells identify infected cells by recognizing pathogen epitopes presented with MHC I molecules on the cell surface. Once an infected cell is recognized, the cytotoxic T cells release perforin and granzymes that penetrate the target cell, inducing a controlled cell death known as apoptosis.
Perforin creates pores in the cell's membrane, while granzymes are proteases that initiate the apoptosis process. This action prevents the spread of infection by ensuring that intracellular pathogens are contained within the dying cell. Therefore, cytotoxic T cells play a crucial role in the immune response against viral infections and in the prevention of cancer progression by targeting and killing infected or abnormal cells before they can replicate or cause significant harm.