Cell Mediated Immunity

Question 1

What is meant by cell mediated immunity?

Answer 1

An immune response that does not involve the production of antibodies.

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

Question 2

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

Answer 2

Cell Mediated Immunity (they are just used to stimulate B-cells in humoral immunity)

Question 3

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

Answer 3

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

Question 4

which type of immunity are B-cells involved in?

Answer 4

involved in humoral immunity, involving antibodies present in bodily fluids, or “humour” such as blood plasma.

Question 5

can B-lymphocytes bind to non-self antigens on antigen presenting cells?

Answer 5

no - only non self antigens floating freely in the blood.

Question 6

what is an antigen?

Answer 6

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

Question 7

what are antigen presenting cells?

Answer 7

cells that display foreign antigens on their surface.

Question 8

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

Answer 8

• 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 9

what is an antibody?

Answer 9

Protein specific to an antigen

produced by B cells/secreted by plasma cells

Question 10

Where are all lymphocytes produced?

Answer 10

Bone marrow

Question 11

Where do T-lymphocytes mature?

Answer 11

In the thymus gland

Question 12

Where do B-Lymphocytes mature?

Answer 12

In the bone marrow.

Question 13

Describe the process of cell mediated immunity (immunity that does not result in the production of antibodies).

Answer 13

1. pathogens invade body cell or phagocytosis of foreign material by phagocyte.
2. Foreign antigens from material are presented on cell surface membrane of phagocyte.
3. Specific T-helper cell receptors (T_h) binds to foreign antigen (clonal selection)
4. Attachment causes T_h 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 secrete antibodies (humoural response)
• activate cytotoxic T cells (T_c) to kill by making holes in cell surface membranes of infected cells.

Question 14

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

Answer 14

• 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 (Tc) to kill by making holes in cell surface membrane of infected cells.

Question 15

How do cytotoxic T lymphocytes (T_c) protect against disease?

Answer 15

They kill cells infected by pathogens or cancerous cells.

They produce a protein called perforin.

Perforin creates holes in target cell membranes, making it permeable to all substances.

cell dies as a result.

Question 16

what is immunity?

Answer 16

the ability of organisms to resist infection by protecting against disease causing micro-organisms or their toxins that invade their bodies.

recognition of foreign material - antigen