Adaptive immunity

Question 1

What 3 cell types are involved in adaptive immunity and what are their functions?

Answer 1

T lymphocytes - immune memory
B lymphocytes - T mediated cytotoxicity
Antigen presenting cells (ARCs) - maintenance of tissue integrity

Question 2

What are the key differences between adaptive and innate immunity?

Answer 2

Adaptive immunity improves over time, is slower in its response and is highly specific

Question 3

Which clustered differentiation markers are present on:

a) B-cells b) Helper T c) cytotoxic T

Answer 3

a) CD40
b) CD4
c) CD8

Question 4

What are the 3 types of T lymphocytes and what are their functions?

Answer 4

T helper (Th) - help activity by releasing cytokines 
T cytotoxic (Tc) - kill infected/abnormal cells 
T regulatory (Treg) - Modulation of immunity and maintenance of self-tolerance

Question 5

How are T helper cells activated?

Answer 5

• Phagocyte consumes bacteria and presents antigen fragments on membrane
• If these fit with the Th receptor it activates and proliferates

Question 6

How are B cells activated?

Answer 6

• B-cells bind with antigens on bacteria
• These are then activated by Th cells to produce plasma and memory cells
• Plasma cells produce antibodies which will make then visible to phacocytes
• Memory cells help activate the immune system faster upon second exposure

Question 7

What are the two main functions of an antibody?

Answer 7

• Neutralize pathogens/toxins

- Act as opsonin

Question 8

What are the main feautures of antibody |gG?

Answer 8

• Most abundant in blood/ectracellular fluid
• Dominant
• Small and hence can cross the placenta

Question 9

What are the main features of antibody IgM?

Answer 9

• Larger and pentameric, hence unstable and tends to break up
• Heavy chains attached by J chain
• Expressed on B cell surface and in the blood

Question 10

How do rises in IgG and IgM change upon first and secodn exposure to a pathogen?

Answer 10

1st - Small immediate rise in IgM followed by second larger rise in IgG
2nd - Same rise in IgM but much larger rise in IgG

Question 11

What are the main features of the IgA antibody?

Answer 11

• Present in external secretions
• Synthesized by plasma cells
• Two antibodies linked by a J chain

Question 12

What are the main features of the IgE antibody?

Answer 12

• Provides protection against pathogens and allergic reactions
• Carbon moietys attached

Question 13

What is the main function of the IgD antibody?

Answer 13

B cell receptor

Question 14

How is the diversity of antibodies generated?

Answer 14

• DNA encoding variable H and L domains are composed of segments
• There is random recombination and gene shuffling within each cell by recombination activating gene (RAG) enzymes
• Undergo further somatic mutation

Question 15

What part of the immune response are the cytotoxic T cells involved in?

Answer 15

Cell mediated response

Question 16

How do Tc cells kill target cells?

Answer 16

• Activated by binding to presented peptide antigen on target cell through CD8 and TCR receptors
• Causes synthesis of perforin and granzymes
• These cluster around the cell membrane causing the formation of pores and hence cell death

Question 17

Describe the structure of T cell receptors

Answer 17

• Variable binding regions and constant transmembrane regions
• Alpha and beta chains linked by a disulphide bridge

Question 18

Describe the structure of the B cell receptor complex

Answer 18

• Y shaped with transmembrane constant regions and variable binding regions
• Light chains and heavy chains

Question 19

What is the major histocompatability complex?

Answer 19

• Identifies uniue self
• Kils virally infected cells
• Presents antigen to T cells

Question 20

What are the two MHC classes and where are they present?

Answer 20

I : present on all cells

II: only found on specific immune cells

Question 21

What role does MHC I play in immunity?

Answer 21

• Presents fragments of viral proteins allowing virally infected cells to be killed
• Double bond of TCR and Tc CD8 to this complex drives apoptosis

Question 22

What role does MHC II play in immunity?

Answer 22

• Binds to fragments of protein taken up by macrophage and exposes them on he cell surface
• Th CD4 binds to these stimulating the proliferation of B cells and the production of specific antibodies