Cell-mediated response

Question 1

What are T-lymphocytes?

Answer 1

A type of white blood cell that is involved in cell-mediated immunity

Question 2

Where are T-lymphocytes made?

Answer 2

In the bone marrow

Question 3

Where are T-Lymphocytes matured?

Answer 3

In the thymus gland

Question 4

Is the cell-mediated response specific or non-specific?

Answer 4

Specific as it responds to an exact antigen

Question 5

Why is this process called the ‘cell-mediated response’?

Answer 5

T cells only respond to antigens which are presented on cells (APC’s) and not antigens detached from cells or within the body fluids

Question 6

What is meant by an ‘antigen presenting cell’?

Answer 6

Any cell that presents a non-self antigen on their surface

Question 7

What are 4 examples of antigen-presenting cells?

Answer 7

• Phagocytes that has engulfed a foreign cell
• Body cells that have been invaded by a virus
• Transplanted cells from individual of the same species
• Cancer cells

Question 8

Describe the process of the cell-mediated response

Answer 8

1. Helper T cells have receptors on their surface which can attach to specific antigens on APC’s
2. Once attached the helper T cells are activated to rapidly divide by mitosis to replicate and make a large number of clones
3. The cloned helper T cells will either:
   
   • Remain as helper T cells and activate B cells
   • Stimulate phagocytes to perform more phagocytosis
   • Become memory cells for that shaped antigen
   • Become cytotoxic T cells
4. Cytotoxic T cells will release a protein called perforin which creates holes in the cell-surface membrane of the infected or abnormal cell and the membrane becomes freely permeable
5. The infected or abnormal cell is therefore destroyed