IMMUNOLOGY

Detailed explanation-1: -Cytotoxic T cells kill their targets by programming them to undergo apoptosis (Fig. 8.35). When cytotoxic T cells are mixed with target cells and rapidly brought into contact by centrifugation, they can program antigen-specific target cells to die within 5 minutes, although death may take hours to become fully evident.

Detailed explanation-2: -A type of immune cell that can kill certain cells, including foreign cells, cancer cells, and cells infected with a virus. Cytotoxic T cells can be separated from other blood cells, grown in the laboratory, and then given to a patient to kill cancer cells.

Detailed explanation-3: -Cytokine Secretion Cytokines are substances that activate other cells. Cytotoxic T cells release two cytokines in particular, TNF-alpha and IFN-gamma, which facilitate the activation of macrophages. The macrophages attack and clean up infected cells and prevent unregulated cell growth such as that of a tumor.

Detailed explanation-4: -The antigen is a peptide fragment generated by antigen-presenting cells when they degrade the foreign protein. To be recognized by a T cell, the antigen must bind a protein called the Major histocompatibility complex (MHC). Cytotoxic T cells recognize antigen bound to MHC protein type 1.