Question

Write short notes on the working mechanism of cytotoxic T cell with suitable diagrams​

Answer 1

Answer:

T cell-mediated cytotoxicity

All viruses, and some bacteria, multiply in the cytoplasm of infected cells; indeed, the virus is a highly sophisticated parasite that has no biosynthetic or metabolic apparatus of its own and, in consequence, can replicate only inside cells. Once inside cells, these pathogens are not accessible to antibodies and can be eliminated only by the destruction or modification of the infected cells on which they depend. This role in host defense is fulfilled by cytotoxic CD8 T cells. The critical role of cytotoxic T cells in limiting such infections is seen in the increased susceptibility of animals artificially depleted of these T cells, or of mice or humans that lack the MHC class I molecules that present antigen to CD8 T cells. As well as controlling infection by viruses and cytoplasmic bacteria, CD8 T cells are important in controlling some protozoan infections and are crucial, for example, in host defense against the protozoan Toxoplasma gondii, a vesicular parasite that exports peptides from the infected vesicles to the cytosol, from which they enter the MHC class I processing pathway. The elimination of infected cells without the destruction of healthy tissue requires the cytotoxic mechanisms of CD8 T cells to be both powerful and accurately targeted.