Cell mediated immunity

Question 1

What is the difference between the specific and the non-specific immune response?

Answer 1

• The non-specific response is the same for all pathogens whereas the specific response is unique to each type of antigen encountered
• The non-specific response is quicker than the specific response
• The specific response creates memory cells and thus leads to immunity, whereas the non-specific response just destroys or prevents pathogens from entering the body

Question 2

Where do T Lymphocytes mature in

Answer 2

Thymus gland

Question 3

What types of cells does cell mediated immunity deal with

Answer 3

Cell meditated immunity deals with infected body cells such as virally infected cells, cancerous cells and antigen presenting cells.

Question 4

Are T helper cells specific or non-specific

Answer 4

Specific

Question 5

Describe the significance of T helper cells being specific

Answer 5

• They bind to complementary antigens, there is a unique response for each type of antigen

Question 6

What do T helper cells target

Answer 6

Infected body cells, such as virally infected cells and cancerous cells

Question 7

What type of lymphocyte produces antibodies?

Answer 7

B-lymphocytes

Question 8

What are antigen presenting cells

Answer 8

Cells that display foreign antigens on the surface

Question 9

When is a foreign antigen is different to antigens present on cells in the body.

Answer 9

• Phagocytes which have engulfed and hydrolysed a pathogen and presented some of the antigens on its surface
• Body cells invaded by a virus presenting viral antigens
• Transplanted cells
• Cancer cells, which are different to normal body cells present antigens on its surface

Question 10

Why can T lymphocytes distinguish these invader cells from normal cells?

Answer 10

• Phagocytes that have engulfed and hydrolysed w pathogen present some of a pathogens antigens in their own cell surface membranes
• Body cells invaded by a virus present some of the viral antigens on their own cell surface membrane
• Transplanted cells from individuals of the same species have different antigens on their cell surface membrane
• Cancer cell are different from normal body cells and present antigens on their cell surface membranes

Question 11

Describe the process of cell mediated immunity

Answer 11

1- When foreign antigens are presented on the surface of a cell, a T helper cell with specific receptors that are complementary to the antigens will bind
- Once the T-helper cell binds, release of chemicals within the T-helper cell activate it. This causes the T-helper cell to divide rapidly by mitosis, producing many identical copies.
2- T helper cells carry out 1/4 functions:
- The first function is to differentiate into T-Memory cells. Memory cells are not usually active - however, if the same antigen enters the body again, these memory cells activate and divide rapidly. They differentiate into T-Helper cells to enable a rapid second response.
- The second function is to activate cytotoxic T-cells. Cytotoxic T helper cells produce a protein called perforin. This protein makes cell membrane more permeable - you saw this in the video earlier. This leads to the death of the cell (apoptosis)
3- The third function is to activate another type of lymphocyte called B-lymphocytes. These cells produce antibodies. Once activated by T-helper cells, B cells rapidly divide by mitosis.
- The fourth function is to stimulate phagocytes to engulf pathogens and increase their production.