Immunology

Question 1

3 patrolling immune cells under the skin surface?

Answer 1

Mast cells, tissue macrophages and dendritic cells

Question 2

Key feature of a pathogen and innate immune cell that allows antigen detection?

Answer 2

PAMPs and PRRs

Question 3

4 key events after organism has breached the skin?

Answer 3

• PAMP binds mast cell PRR and causes release of histamine
• Histamine causes increased vascular permeability and vasodilation
• PAMP binds macrophage/dendritic PRR which causes release of cytokines which attract other WBCs
• Dendritic cells present to helper T cells which activate B cells (connects innate to adaptive)

Question 4

What is the main cell of the innate immune response?

Answer 4

Neutrophil

Question 5

What cells are involved in the clearance of bacteria and fungi?

Answer 5

Macrophage + neutrophil

Question 6

Macrophage action of killing + what 3 things are secreted after + secretion role?

Answer 6

• Pulls pathogen into lysosome containing ROS which destroys pathogen
• Macrophage releases TNF alpha, IL-1 and IL-8 which promote inflammation and recruit neutrophils

Question 7

What attracts neutrophils to infection site + maintenance of neutrophil levels?

Answer 7

• Macrophages release TNF alpha + IL-8
• Neutrophils release TNF alpha to attract more neutrophils (positive feedback)

Question 8

2 extracellular + 2 intracellular neutrophil killing mechanisms?

Answer 8

• NETs trap pathogens until macrophage can phagocytose + degranulation by releasing toxic chemicals
• Phagocytosis + ROS-dependent killing

Question 9

Examples of ROS and how they are made?

Answer 9

• NAPDH oxidase + oxygen = OO (superoxide)
• OO + NO = peroxynitrite (ONOO)

Question 10

How many proteins in the complement system?

Answer 10

30

Question 11

Where are complement proteins made?

Answer 11

In the liver

Question 12

What initiates the classical complement pathway?

Answer 12

IgG and IgM binding C1

Question 13

What initiates the alternative complement pathway?

Answer 13

IgA or gram -ve bacteria

Question 14

Complement cascade summary?

Answer 14

• Runs in order e.g. C1, C2 etc.
• CRP primes bacteria for destruction via complement response
• C3 produces C3a and C3b
• Can also be cleaved by mannose-binding lectin
• C3b degrades unless bound to a cell surface
• Bound C3b cleaves C5 into C5a and C5b
• C5b-C9 = MAC which punctures cells to cause lysis

Question 15

Role of C3a and C5a?

Answer 15

Cause release of pro-inflammatory mediators

Question 16

Name 4 opsonins?

Answer 16

CRP, C3b IgM and IgG

Question 17

Transendothelial migration summary?

Answer 17

• Vasodilation via histamine allows WBCs to move to margins of vessels
• Increased expression of selectins (ICAM and VCAM) via TNF-alpha and IL-1 binds to integrins on WBC
• Interaction is initially weak so rolling occurs but then affinity increases
• WBCs move out of vessel via diapedesis helped by VEGF
• Chemotaxis of WBC to site of injury

Question 18

What acute cell controls virally infected or cancer cells?

Answer 18

NK cells

Question 19

How NK cells detect viral/cancer cells + killing action + what is secreted after + 2 effects of secretion?

Answer 19

• Infected cell releases IFN alpha/beta which activates NK cells
• NK cells use perforin to puncture cell
• NK cells produce IFN gamma which increases macrophage ROS production and general expression of MHC II

Question 20

What controls worm infections?

Answer 20

Mast cells

Question 21

What 2 ways do mast cells clear parasites?

Answer 21

Degranulation or increasing gene expression for pro-inflammatory mediators

Question 22

Primary and secondary lymph tissue?

Answer 22

Primary = bone marrow and thymus/ secondary = tonsils and spleen

Question 23

Site of B cell maturation?

Answer 23

Bone marrow

Question 24

Site of T cells maturation?

Answer 24

Thymus

Question 25

Igs on a naive B cell?

Answer 25

IgM and IgD

Question 26

How B cells reach GC + activation + effect of activation?

Answer 26

- Enter lymph nodes via HEVs - Activated by T cell + antigen in GC - B cells changes to plasma cell and makes higher affinity IgG/A/E

Question 27

Membrane bound Igs?

Answer 27

IgM and IgD

Question 28

Soluble Igs?

Answer 28

IgG, IgA and IgE

Question 29

Antibody structure?

Answer 29

- Y shape with outer lighter chain and inner heavy chain - Hinge region held by disulphide bond - Fc region at the stalk and variable region at ends of both branches

Question 30

Order of Ig abundancy?

Answer 30

GAMDE

Question 31

3 roles of IgG?

Answer 31

Immune complex formation, foetal protetion, complement activation

Question 32

3 roles of IgA?

Answer 32

Mucus membrane protection, most produced Ig and activates alternative complement cascade

Question 33

4 roles of IgM?

Answer 33

Pentamer when secreted, immune complex formation, complement system activation, first Ig produced in infection

Question 34

Role of IgD?

Answer 34

Activates B cell

Question 35

3 roles of IgE?

Answer 35

Protects against helminthes/protozoa, mediates allergic responses, triggers histamine release

Question 36

2 things needed for T cell activation + requirement?

Answer 36

- MHC complex + APC co-stimulatory molecule - Only accept peptides presented by MHC class I or II

Question 37

Cells with MHC class I and what they present to?

Answer 37

All nucleated cells and CD8+ T cells

Question 38

Cells with MHC class II and what they present to?

Answer 38

APCs and CD4+ T cells

Question 39

What cells do CD4+ T cells activate?

Answer 39

CD8 + T cells, macrophages and B cells

Question 40

Role of TH0?

Answer 40

Releases IL-2 to cause CD4+/CD8+ T proliferation

Question 41

Role of TH1?

Answer 41

Releases IFN gamma to increase macrophage ROS production

Question 42

Role of TFH?

Answer 42

Stimulates GC reaction which causes B cells to become plasma cells and undergo Ig class-switching

Question 43

Function of CD8+ T cells + 2 ways they kill?

Answer 43

Kill viral/cancer cells via Fas or perforin protein

Question 44

Special dendritic cell feature+ how they link innate and acquired immunity?

Answer 44

- Expresses MHC class I and II - MHC + APC co-stimulatory molecule activates T cells - T cells activate B cells

Question 45

Causes of the features of inflammation?

Answer 45

Rubor and calor = vascular permeability, tumor = loss of water via increased permeability, dolor = fluid pushing on nerve ending and loss of function

Question 46

What regions of a T cell TCR binds MHC?

Answer 46

Alpha and beta

Question 47

What key IL inhibits inflammation?

Answer 47

IL-10

Question 48

What molecule increases APC co-stimulatory molecule expression?

Answer 48

TNF-alpha

Question 49

What cells have IgE receptors?

Answer 49

Mast cells and basophils

Question 50

Do neutrophils or macrophages live longer?

Answer 50

Macrophages

Question 51

How is NF-kB activated + 2 roles?

Answer 51

T or B cell activation + T cells maturation and cytokine production

Question 52

IL that recruits neutrophils?

Answer 52

IL-8

Question 53

IL that promotes CD4+ and CD8+ T cell proliferation?

Answer 53

IL-2

Question 54

2 things that activate T cell vs B cell?

Answer 54

MHC/antigen complex + APC co-stimulation signal vs helper T cell signal + antigen

Question 55

What forms the MAC?

Answer 55

C5b-C9

Question 56

What complement protein is measured in suspected infection?

Answer 56

CRP

Question 57

Function of TREG cells + disease associated with mutation?

Answer 57

Inactivates T cells + IPEX syndrome

Question 58

IL that stimulates IgE production and Fce receptor expression?

Answer 58

IL-13

Question 59

IL that stimulates eosinophil production?

Answer 59

IL-5

Question 60

IL that stimulates TH1 and inhibits TH2 cells?

Answer 60

IL-12

Question 61

IL that activates B cells to produce IgE?

Answer 61

IL-4

Question 62

Role of cytokine vs chemokine?

Answer 62

Modulate cell behaviour vs allow chemotaxis/ guide WBCs to area of infection