Lecture 13- Immune System

Question 1

Primary lymphoid organs

Answer 1

• Foetal liver
• Bone marrow
• Thymus

Question 2

Secondary lymphoid organs

Answer 2

• Lymph nodes
• Spleen
• Peyers patches
• Adenoid/tonsils
• Appendix

Question 3

Innate

Answer 3

localised/non-specific/ no memory

Question 4

Adaptive

Answer 4

7 days after pathogen entry / specific /induces memory response
- T/ B/ Ce cells
No adaptive response without innate response

Question 5

Complement System

Answer 5

part of Humoural system
Cascade of proteins circulation in your blood and 3 specific pathway
- Classical pathway
- MB-Lectin pathway
- Alternative pathway
All merge into C3 Convertase – formed upon activation of these pathways
Aim is to punch a hole on the pathogen and lyse the cell

Question 6

Cytokines

Answer 6

peptides that communicate within the immune system and with host tissue cells
Can be inflammatory or not
Eg. IL-1Beta, TNFalpha
Systemic or local effects

Question 7

tumour cells benefit…

Answer 7

Tumour cells benefit trying to suppress cytotoxic T cells

- Immunosuppress environment

Question 8

Granulocytes

Answer 8

-	Neutrophils -Phagocytic
When exposed to bacteria can just chuck DNA out 
Short lived 
-	Eosinophils
Histamine release 
-	Basophils

Question 9

Macrophages-

Answer 9

APC

• Mononuclear
• Circulating
• Phagocytic
• Cytokine secretion to recruit other effector cells
• Present extracellular pathogens on MHC11
• MHC1 all contents on its outer surface

Question 10

Dendritic cells – APC

Answer 10

• Activate naïve T cells
• Link innate and adaptive immune response
• Cytokine production – dependent on the pathogen
• Pattern recognition receptors

Question 11

B cells

Answer 11

• Mediators of the humoral response

Question 12

NK Cells

Answer 12

• Spontaneous killing via perforin and granzyme B
• Induce apoptosis
• Regulate multiple types of cells
• Activator receptors
• Inhibitory receptors
• Tumour infiltrating NK cells usually improve prognosis

Question 13

T Cells

Answer 13

• Mediators of cellular immunity , express antigen specifc TCR
• Develop in the thymus
• Memory cells

Question 14

TH1

Answer 14

Help to eradicate infections that can survive or replicate within macrophages, e.g. bacteria that can escape intracellular killing
TH1 cell recognises the bacterial antigen displayed on the surface of the macrophage, it will produce IFNg, which enhances the microbial activity of the macrophage

Question 15

TH2

Answer 15

Control infection by extracellular parasites by promoting activation of eosinophils, mast cells
IL-4/5/13 production

Question 16

TH17

Answer 16

Respond to extracellular bacteria and fungi
Amplify neutrophil response
IL-17 and IL-22 production that activates anti-microbial peptide production by barrier epithelial cells

Question 17

Tfh

Answer 17

Provide help to B cells and promote germinal centre formation
Localised in the lymphoid follicles, prime type 1/2/3 responses
Promote B-cell class-switching

Question 18

Treg

Answer 18

Limit the immune response and prevent autoimmunity
Natural subset – develops in the thymus, induced subset – develops on the periphery from CD4+ cells
FoxP3 expression – prevents AP-1 and NFAT activation, thus IL-2 induction

Question 19

CD8+ cytotoxic T cells

Answer 19

Kill infected cells

Are identified by the surface marker CD8 (CD8+ T-cells)

Control intracellular pathogens such as viruses and bacteria

Require cell to cell contact to bind antigen

Bind only antigen presented on the surface of cells