3. Fundamentals in Immunology

Question 1

What are the three layers of immune response?

Answer 1

Anatomical and physiological barriers
Innate responses
Adaptive responses

Question 2

What is a pathogen?

Answer 2

A micro-organisms that causes disease

Question 3

Name some anatomical and physiological barriers (Immune response)

Answer 3

Skin
Mucous
Stomach acid
Lysozyme

Question 4

Give some examples of Innate immune response

Answer 4

Mast cells
Recruitment of phagocytic cells
Complement cascade

Question 5

How do Mast Cells work in terms of innate immunity?

Answer 5

They cause changes in the blood vessel wall that make it ‘sticky and leaky’. This allows more fluids and proteins like complement to enter the tissues.

Question 6

How does Recruitment of phagocytic cells work in terms in innate immunity?

Answer 6

Neutrophils and monocytes are recruited to engulf and kill the pathogen. The changes in the blood vessel (Mast cells) allows these cells to leave the blood and enter the tissue

Question 7

What is Complement Cascade?

Answer 7

Complex system (cascade) of reactions that act in a sequential manner to trigger an immune response

Question 8

How do adaptive immune responses compare to innate immune responses?

Answer 8

Adaptive responses are slower, but more specific and more effective

Question 9

How does the immune system travel around the body?

Answer 9

Through the blood and lymph circulation

Question 10

Where do immune cells come from?

Answer 10

Immune cells (Leukocytes)(White blood cells) come from Hematopoietic stem cells, which are produced in the bone marrow

Question 11

How are T cells made?

Answer 11

By maturation of Hematopoietic stem cells in the Thymus

Question 12

How are B cells made?

Answer 12

By maturation of Hematopoietic stem cells in the Bone marrow

Question 13

Where are neutrophils, macrophages and dendritic cells derived from?

Answer 13

Hematopoietic stem cells

Question 14

What are the different Leukocytes?

Answer 14

Granulocytes (Eosinophil, Basophil, Neutrophil)
Monocytes (Dendritic cell and Macrophage precursor)
Lymphocytes (B cells and T cells)

Question 15

What do Mast cells do?

Answer 15

Raise the alarm, release toxic molecules

Question 16

What do Neutrophils do?

Answer 16

Release toxic molecules, engulf and kill bacteria

Question 17

What do macrophages do?

Answer 17

Engulf and kill bacteria, alert the immune system of the presence of an infection tissue repair and wound healing

Question 18

What do dendritic cells do?

Answer 18

Engulf and kill bacteria/viruses, migrate to lymph node and activated adaptive responses

Question 19

What do B cells do?

Answer 19

Secrete antibodies
Kill bacteria
Opsonise pathogens
Neutralise pathogens

Question 20

What do Cytotoxic T cells do?

Answer 20

Kill viral infected cells

Question 21

What do T helper cells do?

Answer 21

Provide cytokines and other stimulatory signals to B cells, Cytotoxic T Lymphocytes and macrophages

Question 22

What is a PAMP?

Answer 22

Pathogen-Associated Molecular Patterns

Question 23

What are the common features of PAMPs?

Answer 23

Not found in multicellular hosts
Present on numerous groups of pathogens
Not frequently mutated
Recognised by ‘Pattern Recognition Receptors’

Question 24

Give some examples of PAMPs

Answer 24

Double stranded RNA
Viral DNA
Glycoproteins
Bacterial DNA
Polysaccharides
Glycolipids

Question 25

What are the stages of phagocytosis?

Answer 25

``` Internalisation Acidification Lysosome fusion Toxic contents Pathogen death ```

Question 26

What are cytokines?

Answer 26

Small soluble proteins (rapidly secreted by one cell after contact with specific antigen) that can alter the behaviour or properties of the cell itself or another cell

Question 27

What are chemokines?

Answer 27

Family of small cytokines that can promote chemotaxis

Question 28

What is chemotaxis?

Answer 28

Movement of an organism in response to a chemical stimulus

Question 29

What are the two ways the complement proteins can be activated?

Answer 29

Classical pathway - antibody dependent, part of adaptive response Alternative pathway - part of the immune response

Question 30

What is a Protein Kinase?

Answer 30

A kinase enzyme that modifies other proteins by chemically adding a phosphate group to them.

Question 31

What are the two conventional T cells?

Answer 31

CD4 (MHC II) | CD8 (MHC I)

Question 32

What do conventional T cells do?

Answer 32

Recognise peptides present on MHC II or MHC I

Question 33

What are the different kinds of unconventional T cells?

Answer 33

Natural Killer T cell (NKT) Mucosal Associated Invariant T cell (MAIT) γδ T cell

Question 34

What do unconventional T cells do?

Answer 34

Recognise pathogen product on non-classical MHC molecules or as free antigens

Question 35

What are CD4 T cells?

Answer 35

Helper T cells

Question 36

What are CD8 T cells?

Answer 36

Cytotoxic T cells

Question 37

What is an antigen?

Answer 37

A catch-all term for the molecules that B or T cells recognise through their B cell receptor or T cell receptor

Question 38

Where are Natural Killer T cells found?

Answer 38

Found throughout the body

Question 39

Where are Mucosal-Associated Invariant T cells found?

Answer 39

Mainly found in mucosal sites (e.g. the gut)

Question 40

Where are γδ T cells found?

Answer 40

Often found in mucosal sites and in the skin

Question 41

What is Somatic Rearrangement?

Answer 41

An alteration of the DNA of a somatic cell that is inherited by its daughter cells

Question 42

Where is Somatic rearrangement often found?

Answer 42

In the assembly of B cell receptors and T cell receptors

Question 43

What are the key events in thymic development?

Answer 43

Commitment to T cell lineage Generation of unique TCR molecules Positive selection Negative selection

Question 44

What is a thymocyte?

Answer 44

Hematopoietic progenitor cell

Question 45

What is positive T cell selection?

Answer 45

TCRs of mature T cells bind to self-antigens

Question 46

What is negative T cell selection?

Answer 46

Removal of T cells that recognise the body's own proteins

Question 47

What do Natural Killer T cells do?

Answer 47

Kill infected cells

Question 48

What do Mucosal-Associated T cells do?

Answer 48

Amplify immune response

Question 49

What do γδ T cells do?

Answer 49

Amplify or regulate immune response

Question 50

What is the process of CD4 and CD8 T cell response?

Answer 50

1. Pathogens infect tissues 2. Activated DCs move to lymphoid organs carrying the pathogen 3. DCs activate antigen specific T cells 4. T cells proliferate 5. T cells migrate out of the lymph node 6. T cells migrate to infected tissues to clear infection

Question 51

What is an Afferent lymph node?

Answer 51

Where cells come in from the tissue (Arrive)

Question 52

What is an Efferent lymph node?

Answer 52

Where cells leave the lymph node (Exit)

Question 53

What happens in the paracortex of the lymph node?

Answer 53

DCs from the tissue meet CD4 and CD8 T cells

Question 54

What happens in the B cell follicles?

Answer 54

Germinal centres for here during immune responses

Question 55

What are dendritic cells?

Answer 55

Act as messengers between the innate and adaptive immune systems. They process antigen material and present it on the cell surface to T cells

Question 56

What is a germinal center?

Answer 56

A site within secondary lymphoid organs where mature B cells proliferate, differentiate and mutate their antibody genes.

Question 57

What two key events do T cell activation lead?

Answer 57

Proliferation | Differentiation

Question 58

What are the three (continuous) signals required in T cell activation?

Answer 58

Peptide-MHC Co stimulation Cytokine Receptor

Question 59

What is the process in which T cells are activated by Dendritic cells?

Answer 59

1. PRR triggering enhances phagocytosis 2. Pathogens are digested inside endosomes 3. MHc molecules inside endosomes meet pathogen-containing endosomes 4. MHC molecules containing peptides from pathogen are presented on the cell surface 5. PRR triggering causes the Dendritic cell to migrate from the tissue to the draining lymph node 6. PRR triggering also causes the DC to express high levels of costimulatory molecules and make inflammatory cytokines

Question 60

Give some examples of Co-stimulation molecules

Answer 60

Peptide-MHC and TCR | CD80/CD86 and CD28

Question 61

How can T cells be stopped?

Answer 61

Ignorance Presentation of antigen by resting DC Regulatory T cells

Question 62

How does T cell ignorance occur?

Answer 62

T cells cannot access antigens in immune privileged sites

Question 63

How does presentation of antigen by resting DC stop a T cell?

Answer 63

T cells die or become non-functional if only activated by one signal

Question 64

What is Perforin?

Answer 64

Cytolytic protein found in granules of cytotoxic T cells and NKT's. Pokes holes in the infected cell