5.3 - T lymphocytes and cell-mediated immunity

Question 1

Functions of cloned T Cells (4 points):

Answer 1

• develop into memory cells
  circulate in the body - provides long term immunity
• stimulate phagocytosis
  cloned cells stimulate phagocytes to engulf pathogens
• stimulate division of B cells
  cloned cells stimulate B cells to divide and produce antibodies
• activate cytotoxic T Cells
  allows TC cells to kill infected cells

Question 2

Stages of the cellular response:

Answer 2

• phagocyte engulfs pathogens - display their antigens on the cell-surface (APCs)
• Helper T Cells with complementary receptors bind to these antigens
• On binding - TH cells activate to divide by mitosis to form genetically identical clones

Question 3

What do Memory T Cells do (what does it provide against pathogens, how quick is the response and why is this):

Answer 3

• provides long-term immunity against specific pathogens

provides a rapid response if body is re-infected by the same pathogen

Question 4

What are cytotoxic T cells (what do they kill and how do they kill, what does perforin protein do and what does it become and cause):

Answer 4

• kill abnormal and foreign cells
  1. through producing perforin
  2. protein makes holes in the cell-surface membrane
  3. causes it to become freely permeable and causes cell death

Question 5

What are Helper T Cells (what do they contain and what do they form and stimulate):

Answer 5

• have receptors on their cell-surface that binds to complementary antigens on APCs
  1. form memory cells
  2. stimulate B cells or phagocytes - activates cytotoxic T Cells

Question 6

2 types of lymphocytes: (where does it mature and what is it involved in)

Answer 6

1. T lymphocyte - matures in the thymus gland
   * involved in cellular response when APCs are present
2. B lymphocytes - matures in the bone marrow
   * involved in humoral response - produces antibodies found in body fluids (humorous)