Week 7

Question 1

physical barriers

Answer 1

Skin 
Mucus 
Acid in gut 
Enzymes in secretions 
Commensal bacteria

Question 2

soluble responses

Answer 2

circulating proteins that can recognise pathogen, deal with pathogen or assist in this

Question 3

cellular responses

Answer 3

range of immune cells that can recognise and deal with pathogen

Question 4

Cells associated predominantly with innate immunity

Answer 4

myeloid lineage

Question 5

cell migration events

Answer 5

docking (rolling), adhesion, migration (extravasation)

Question 6

How do our immune cells recognise a pathogen?

Answer 6

Pathogen recognition receptors (PRRs)

Question 7

What features of pathogens do we recognise?

Answer 7

Pathogen associated molecular patterns (PAMPS)

Question 8

PAMPS

Answer 8

Structures associated with pathogens and not found in our tissues
Important for survival of a pathogen as a species

Question 9

toll like receptors (TLRs)

Answer 9

A family of PRRs
Innate receptors found in vertebrates and invertebrates
In vertebrates TLRs are found on cell surface and intracellularly

Question 10

phagocytes

Answer 10

neutrophil; macrophage; dendritic cell

Question 11

steps in phagocytosis

Answer 11

Recognition of pathogen (PRR: PAMP)
Engulfment in phagosome
Fusion of phagosome with lysosome (contains destructive cocktail of substances like enzymes and reactive oxygen species)
Generation of phagolysosome exposes pathogen to lysosome content (destruction of pathogen)

Question 12

Granulocytes

Answer 12

Deals with pathogens that are too large to engulf
Intracellular granules which contain cocktail of destructive substances
Act by releasing their granules onto the surface of pathogen (degranulation)
Many cells work together to achieve this

Question 13

key mechanisms of innate immunity

Answer 13

phagocytes- phagocytosis
granulocytes- degranulation
complement- promotes phagocytosis, cell destruction

Question 14

antigen processing and presentation

Answer 14

dendritic cells capturing pathogen and processing it so that T cells can be activated

Question 15

MHC Class I

Answer 15

expressed on all nucleated cells of body

Question 16

MHC Class II

Answer 16

expressed by DC, macrophages, B cells

Question 17

MHC Class I explain

Answer 17

Presents pathogen proteins that are found in the cytoplasm
For a DC initiating the immune response, it presents to CD8 T cells (which only recognise MHC Class 1+ peptide)
For other cells of the body,, if they are infected with virus, they use this MHC to display viral peptide to be recognised by the cytotoxic CD8 T cell for killing

Question 18

MHC Class II

Answer 18

Processes and presents pathogen proteins that originate from outside the cell
For a dendritic cell initiating a response (bacteria or dead infected cells) it presents to CD4 T cells (only recognises MHC Class II + peptide)
Activated CD4 T cells are also called helper T cells
They help CD8 T cells become better cytotoxic T cells
They help B cells secrete the right type of antibody

Question 19

autoimmunity

Answer 19

based on the process of recombination, we will also generate receptors on T and B cells that could react to our own tissues and cause self reactive immunity
This requires a mechanism of immune tolerance to prevent this

Question 20

T cells develop

Answer 20

thymus

Question 21

B cells develop

Answer 21

bone marrow

Question 22

During development t cells undergo tests

Answer 22

If they fail to make a TCR receptor they die
If they make a functional TCR that can recognise the MHC they survive (Positive selection)
During this development process the antigen receptors on T cell can sample our own molecules in the thymus

Question 23

Negative selection t cells

Answer 23

If interaction of the receptors and self molecules is very strong, the cell is triggered to die
This removes many of the self reactive T cells that are generated because of the random nature that recombination generates unique receptors

Question 24

IgD

Answer 24

found on surface of B cells

Question 25

IgG

Answer 25

single unit secreted in high amount into the circulation and important against bacterial and viruses can cross placenta to baby

Question 26

IgE

Answer 26

single unit and found mainly attached to the surface of Mast cells epithelial layers

Question 27

IgM

Answer 27

large and made up of 5 singles units joined at the tail | blood circulation

Question 28

IgA

Answer 28

dimer and actively transported across epithelial surfaces found in respiratory, gastrointestinal system etc.; transported in breast milk

Question 29

neutralisation

Answer 29

antibodies bind to bacteria and prevent their invasion or entry

Question 30

opsonisation

Answer 30

coating of pathogen by antibody

Question 31

2 parts of the viral life cycle

Answer 31

Intracellular: following infection and assembly Extracellular: upon release to infect new cells

Question 32

Humoral response

Answer 32

b cells and antibodies

Question 33

stem cells specialised

Answer 33

into a type of two progenitor cells (myeloid or lymphoid) myeloid are innate cells lymphoid become adaptive cells

Question 34

lymph nodes

Answer 34

Lymph nodes allow cells and fluid from the tissues to drain through the lymph nodes and mount an immune response; the lymph fluid then drains back into the blood circulation When a pathogen is encountered, it is carried to the lymph node by a dendritic cell Within the lymph node there are many T and B cells that continually circulate

Question 35

if infection in blood

Answer 35

taken by dendritic cell to spleen

Question 36

CD8 cytotoxic T cell

Answer 36

only interact with MHC Class I

Question 37

CD4 helper T cells

Answer 37

only interact with MHC Class II

Question 38

t cell antigen receptor

Answer 38

surface of t cells each t cell expresses only 1 type of TCR cannot be secreted

Question 39

amino acid sequence in TCR vary most

Answer 39

in variable region

Question 40

b cell antigen receptor

Answer 40

when expressed on b cell surface, called b cell receptor (BCR) can be secreted to form antibodies

Question 41

B cell antigen receptors regions

Answer 41

variable diverse junctional each B cells chooses one of V D and J genomic segments to make antigen binding site

Question 42

Adaptive immune response

Answer 42

pathogen/antigen captured and DC moves to the lymph node where they can present pathogen Within the lymph node, DC and T cell interact T cell with TCR that recognises the MHC + Peptide will be activated For CD4 T cells this is via MHC Class II, for CD8 T cells this is via MHC Class I Clonal expansion of antigen specific t cells This will generate a group of CD4 T helper cells and a group of CD8 cytotoxic T cells T helper cells will then interact with antigen specific B cells to promote their proliferation B cell can also process and present antigen on surface MHC class II If the TCR on the T cell sees the same MHC+peptide on the B cell as presented by the DC it will activate the B cell to proliferate and secrete antibodies Within the lymph node, the interaction of dendritic cell, T and B cells leads to generation of: CD4 T helper cells; CD8 cytotoxic T cells; antibody producing B cells (plasma cells )

Question 43

monomer AB

Answer 43

igG IgD IgE

Question 44

pentameter AB

Answer 44

IgM

Question 45

dimer AB

Answer 45

IgA

Question 46

Adaptive immune responses are generated in

Answer 46

lymphoid organs