Adaptive Immunity

Question 1

Describe the adaptive response

Answer 1

• Powerful- antigen specific
• Immunilogical memory can be developed
• More rapid subsequent encounters
• Follows the induction of innate immunity
• System in the lymph nodes

Question 2

What are the advantages of the adaptive response?

Answer 2

• High antigen specificity
• Highly effective
• Memory cells have a quick and effective response at subsequent encounters

Question 3

What are the disadvantages of the adaptive response?

Answer 3

• Takes a few days to develop

- Ineffective for new pathogens, no memory developed

Question 4

Describe innate immunity

Answer 4

• Activated by dendritic cells and macrophage digest bacteria
• Soluble mediators and cytokines
• Activate mast cells (release histamines)
• Types of dendritic cells- langerhan, dermal dendritic cells

Question 5

What is the function of B lymphocytes?

Answer 5

-Differentiates and becomes plasma cells that secrete antibodies

Question 6

What is the function of Helper T cells?

Answer 6

• CD4 receptor

- Helps immune response through releasing chemical signalling to other parts of the immune system

Question 7

What is the function of cytotoxic T cells

Answer 7

• CD8 receptor

- Kill infected cells by releasing cytotoxic granules

Question 8

Describe the activation of adaptive immune response

Answer 8

• 3-14 days
• Bacteria can enter lymph node
• B cells are found in the cortex
• T cells are found in the paracortex
• Activation of the closest point contact, which may be a lymph node

Question 9

Describe the activation of T cells

Answer 9

• Dendritic cells phagocyte bacteria and present fragments complexed with MHC
• MHCs are found on dendritic surface, presented Helper T cell, CD8 to MHC class 1 and CD4 to MHC class 2
• New T cells can only be activated by dendritic cells, after this any antigen cell can activate

Question 10

What does MHC stand for?

Answer 10

Major histocompatibility complex

Question 11

Describe the activation of B cells

Answer 11

• Not fragments, whole antigen
• B cell receptor- antibody bound to membrane, also expresses MHC Class 2
• Binding of antigen to antibody isn’t sufficient for B cell activation, requires helper T cell (IL4)
• Upon activation plasma cells are produced which migrate to medulla of lymph node

Question 12

What occurs in the activation of the adaptive response

Answer 12

• CD8 continues to kill
• When most cells activated, chemokines released that leafe a trail for T cells to callow along lymph vessels
• Long process as it takes time for proliferation to occur and antibodies to be produced
• Antibodies specific and accumulate in bloodstream

Question 13

What occurs in the third phase of adaptive response?

Answer 13

• T cells present much more rapidly than antibodies
• Acquired immunity highly specific, generates more efficient response
• releases chemical signals

Question 14

What is opsonisation?

Answer 14

• Cells chemically modified to have a stronger attraction to cell surface receptors on phagocytes
• Antibodies facilitate phagocytosis
• ADCC- antibody-dependent cellular cytotoxicity

Question 15

What is the resolution of infection?

Answer 15

• Removal of bacteria

- Establishment of memory

Question 16

How is memory established?

Answer 16

• Generation of memory T and B cells
• One of the daughter T cells becomes a memory T cell once infection has died down
• Proliferate more rapidly second time (days rather than weeks)
• Some B cells differentiate into memory cells rather than plasma
• Reside in tissue and lymphoid tissue

Question 17

Why does tetanus infection not usually induce memory?

Answer 17

• Produces a toxin rather than antigen, difficult for immune system to respons

Question 18

Describe the tetanus infection?

Answer 18

• Damages nervous tissue
• Not lifelong memory
• Boosters required
• In vaccination, toxins are attenuates, may not stimulate immune system as much as actual infection