3 - Immune system II: Adaptive Immunity

Question 1

innate immune system

Answer 1

• Non-specific
• Elements present at birth
• Effective against a wide range of pathogens
• Lifelong presence
• Present in all animal species

Question 2

adaptive immune system

Answer 2

• Specific for certain antigens
• Gained after exposure to foreign material
• Delay before effective - 5-6 days to respond
• Memory - faster response to subsequent exposure to same pathogen
• Carried out by Lymphatic system
• Only in vertebrates
• Once acquired, it is lifelong (mostly)

Question 3

cells involved in innate immunity

Answer 3

• innate lymphoid cells
• natural killer cells
• mast cells
• eosinophils
• neutrophils
• macrophages
• dendritic cells (APCs)

Question 4

APCs

Answer 4

Cells that possess MHC class 2, allows them to activate B and T cells

Question 5

Cells involved in adaptive immunity

Answer 5

• lymphocytes
• CD4+ T helper cell
• CD8+ Cytotoxic T cell
• B cell

Question 6

Lymphocytes

Answer 6

• 6 micrometer diameter
• short lifespan
• circulate in blood and lymph
• activated by antigen
• both originate in bone marrow

Question 7

How do immune cells find one another in the body?

Answer 7

through the circulatory and lymphatic system

Question 8

where are lymphocytes made?

Answer 8

primary lymphoid organs:

1. Bone marrow (b cells mature)
2. Thymus (t cells mature)

Question 9

how do immune cells find pathogens, and each other

Answer 9

1. interstitial fluid bayhes tissue and along with blood cells enters the lymphatic vessels
2. lymph flows through lymphatic vessels throughout body
3. within LNs, pathogens and particles in the lymph encounter and activate APCs
4. LVs return lymph to the blood via 2 large ducts that drain into veins

Question 10

What are the secondary lymphoid organs?

Answer 10

spleen and lymph nodes

Question 11

what is the role of the lymph nodes?

Answer 11

They filter lymph.

Question 12

what is the role of the spleen?

Answer 12

filters blood

Question 13

humoral response role

Answer 13

defends against pathogens and toxins in extracellular fluid

Question 14

cell-mediated response role

Answer 14

defend against infected cells, cancer cells and transplanted

Question 15

antigen

Answer 15

any foreign molecule which is specifically recognised by lymphocytes and elicits a response by them

Question 16

how do lymphocytes detect antigen?

Answer 16

by the B and T cell receptors embedded in their respective membranes, as each is specific for 1 epitope

Question 17

b cell activation - humoral response

Answer 17

1. Developing B cells undergo a selection process in bone marrow: self-reactive cells are destroyed
2. Mature B-cells released from bone marrow
3. receptor interacts directly with pathogen
4. affinity maturation

Question 18

Antibody subclasses

Answer 18

IgM, IgG, IgE, IgA, IgD

Question 19

why do we have booster vaccinations?

Answer 19

the secondary response to antigen is faster, greater and of increased duration

Question 20

what are the effector cells of the adaptive immune response?

Answer 20

t lymphocytes

Tc cells : defend against infected cells, cancer cells and transplanted cells

B lymphocytes: secrete antibodies, present antigen to activate T cells

Question 21

how do T cells develop?

Answer 21

1. Developing T cells undergo two selection processes, positive then negative selection
   positive: cells that don’t recognise self MHC
   negative: cells that recognise self too strongly
2. mature cells become either Tc cells or Th cells

Question 22

how do T cells get activated?

Answer 22

By recognition of antigen presented on MHC molecules
CTL activated by presented antigen from infected cell
TH cell activated by antigen
presented by Antigen Presenting Cell