3.2.4.3 Cell Mediated Immunity

Question 1

Which type of immunity are T-lymphocytes mainly involved in?

Answer 1

Cell mediated immunity

they are just used to stimulate B cells in humoral immunity

Question 2

Where can non-self antigens be found that T lymphocytes may bind to?

Answer 2

• The surface of an antigen presenting cell (phagocyte)
• Body cells invaded by a virus may present viral
  antigens
• Transplanted cells from organ donors
• Cancer cells
• Toxins produced by pathogens

Question 3

Can T lymphocytes bind to non-self antigens floating around freely in the blood?

Answer 3

No - they can only bind foreign antigens that have been presented on an antigen presenting cell e.g. phagocyte

Question 4

How do cytotoxic T lymphocytes protect against disease?

Answer 4

They kill cells infected by pathogens or cancerous cells.

They produce a protein called perforin

Perforin creates holes in target cell membranes, which kills the cell

Question 5

Where do T lymphocytes mature?

Answer 5

In the thymus

Question 6

Where are all lymphocytes produced?

Answer 6

Bone marrow

Question 7

Where do B lymphocytes mature?

Answer 7

In the bone marrow

Question 8

What is meant by cell mediated immunity?

Answer 8

An immune response that does not involve the production of antibodies

Results in the production of cytotoxic T cells that can protect against pathogens

Question 9

Describe the process of cell mediated immunity

immunity that does not result in the production of antibodies

Answer 9

1. Phagocytosis of foreign material by phagocyte
2. Foreign antigens from material are presented on phagocyte
3. Specific T-helper lymphocyte binds to foreign antigen (clonal selection)
4. Attachment causes T helper cell to undergo mitosis (clonal expansion)
5. Cloned T cells can:

• Become memory cells for rapid future response to same pathogen
• stimulate phagocytes to engulf via phagocytosis
• stimulate B cells to divide and release antibodies (humoural response)
• activate cytotoxic T cells to kill

Question 10

What can the cloned T lymphocytes do after clonal expansion has taken pace in the cell mediated response?

Answer 10

• Become memory cells for rapid future response to same pathogen
• Stimulate phagocyte to engulf via phagocytosis
• stimulate B cells to divide and release antibodies (humoural response)
• activate cytotoxic T cells to kill

Question 11

What is an antigen?

Answer 11

Foreign protein that can stimulate an immune response / production of antibodies

Question 12

What is an antibody?

Answer 12

Protein specific to an antigen

Produced by B cells / secreted by plasma cells