T killer cell activation- lqc 5b

Question 1

in what situation do T killer cells need to be activated

Answer 1

when a bacterium or virus has infected a host body cell

Question 2

describe how a T killer cell is activated

Answer 2

1. . A bacterium or virus with antigens on its surface infects a host body cell.
2. The host cell carries out antigen processing and presentation. Antigen is bound to an MHC protein. The host cell has now become an antigen-presenting cell (APC).
3. T killer cell with a complementary receptor binds to the antigen/MHC complex. In the presence of cytokines released from active T helper cells, the T killer cell will be activated and stimulated to divide by mitosis.
4. Some active T killer cell clones differentiate and divide to form T killer memory cells. These remain dormant until they are used in the secondary immune response when the antigen is encountered again.
5. Population of active T killer cell clones created.
6. Active T killer cells bind to other infected host cells which are presenting antigen (APCs)
7. Active T killer cell releases enzymes (e.g. perforins) that create pores in the infected host cell membrane. Water and ions enter the cell, causing cell lysis (it swells and bursts) destroying the host cell. Any live pathogens with the host cell are released. Antibodies bind to the antigen on the pathogen surface (opsonisation) for destruction by macrophages in phagocytosis

Question 3

what is the role of macrophages following host cell destruction by T killer cells?

Answer 3

They carry out phagocytosis of agglutinated pathogen (pathogen clumped together by antibodies) following cell lysis. They phagocytose host cell debris following cell lysis.

Question 4

Within the specific primary immune response, activation of T killer cells, followed by the lysis of infected host cells is known as?

Answer 4

the cell mediated response