Final answer:
Cell-mediated immunity involves cytotoxic T cells (Tc cells) that detect and destroy virus-infected or cancerous cells. These T cells recognize antigens presented by MHC I molecules, triggering the release of perforin and granzymes, which induces apoptosis in the target cells. This precise mechanism ensures the elimination of harmful cells while preserving nearby healthy cells.
Step-by-step explanation:
How Cell-Mediated Immunity Destroys Diseased and Cancerous Cells
Cell-mediated immunity involves a specific set of immune cells known as T cells, particularly cytotoxic T cells (Tc cells), which play a crucial role in the defense against diseased and cancerous cells. The process begins when Tc cells recognize abnormal cells, such as virus-infected cells or cancerous cells, with the help of unique proteins and tumor antigens they display. These abnormal cells present specific epitopes in conjunction with MHC I molecules on their surface, signaling the Tc cells to target them.
Once activated, Tc cells bind to the infected or cancerous cells and release toxic substances, such as perforin and granzymes. Perforin creates pores in the target cell membrane, and granzymes enter through these pores to induce apoptosis, a form of programmed cell death. This mechanism efficiently eliminates the abnormal cells without releasing pathogens, which prevents further infection of neighboring cells and controls the spread of the disease.
Additionally, cell-mediated immunity supports the functions of natural killer (NK) cells in eliminating early-stage cancers. The T cells and NK cells working in synergy, along with cytokines produced by helper T cells (Th1 response), enhance the immune response against infected cells and tumors. This content loaded explanation illustrates how the intricate and precise nature of cell-mediated immunity specifically targets and eradicates diseased and cancerous cells.