Question

Cytotoxic T cells focus their killing machinery on target cells through a process called polarization. The cytoskeleton and the cytoplasmic vesicles containing lytic granules are oriented toward the area on the target cell where peptide:MHC class I complexes are engaging T-cell receptors. In the T cell, the microtubule-organizing center (MTOC), Golgi apparatus (GA), and lytic granules, which contain cytotoxins, align toward the target cells. The lytic granules then fuse with the cell membrane, releasing their contents into the small gap between the T cell and the target cell, resulting in the deposition of cytotoxins on the surface of the target cell. The cytotoxic T cell is not killed in this process and will continue to make cytotoxins for release onto other target cells, thereby killing numerous target cells in a localized area in succession. The cytotoxins include perforin, granzymes, and granulysin, molecules that induce apoptosis (programmed cell death) of the target cell.

1) True
2) False

Answer 1

The student's question accurately describes the biological mechanism by which cytotoxic T cells identify and destroy infected cells through antigen presentation, followed by release of cytotoxins such as perforin and granzymes to induce apoptosis. This targeted immune response allows for the destruction of infected cells without harm to the cytotoxic T cells themselves.It is true.

Step-by-step explanation:

The process described in the student's question is true. Cytotoxic T cells (CTLS) indeed use a specialized and targeted approach to eliminate infected cells. The mechanism they employ involves recognizing infected cells through MHC I-epitope complexes and responding by polarizing their release machinery toward the cell. This involves the orientation of the microtubule-organizing center (MTOC), Golgi apparatus (GA), and lytic granules towards the target cells.

Lytic granules contain perforin, granzymes, and granulysin, which cooperate to induce apoptosis, effectively annihilating the infected cell while preserving the CTLS for further action. This process is similar to that used by Natural Killer (NK) cells, except that CTLS recognize specific antigens presented by the MHC I complex.

CTLS are essential in fighting viral infections by stopping the replication of viruses within infected cells, thus preventing the spread of infection. Moreover, they can kill multiple infected cells due to their capacity to continually produce cytotoxins. The immune response benefits greatly from the complementary actions of both CTLS and NK cells, effectively maximizing the elimination of infected cells.