[W8] Signalling in the immune system

Question 1

What triggers immune cell signalling?

Answer 1

Signals from pathogens, cytokines, and other immune cells

Question 2

What is signal integration in immune cells?

Answer 2

Combining multiple signals (e.g., Ras/MAPK, PI3K/Akt) to determine cell fate

Question 3

What are cytokines?

Answer 3

Small secreted proteins that mediate immune cell communication

Question 4

What are the three main types of cytokines?

Answer 4

• Innate immunity cytokines (e.g., TNF, IL-1)
• Adaptive immunity cytokines (e.g., IL-2, IL-10)
• Chemokines (control cell migration)

Question 5

What do cytokines control in immune cells?

Answer 5

Recruitment, activation, proliferation, and differentiation

Question 6

What is the JAK-STAT pathway?

Answer 6

A signalling cascade where JAKs phosphorylate STATs, which then regulate gene expression

Question 7

What activates JAK kinases?

Answer 7

Cytokine binding to their receptors

Question 8

What happens after STATs are phosphorylated?

Answer 8

They dimerise, enter the nucleus, and bind DNA to modulate transcription

Question 9

What triggers B cell signalling?

Answer 9

Antigen binding to the B Cell Receptor (BCR)

Question 10

Which pathways are used in BCR signalling?

Answer 10

• Ras/MAPK
• PI3K/Akt
• PLCγ

Question 11

What do B cell co-receptors do?

Answer 11

Fine-tune signalling to determine activation, tolerance, or anergy

Question 12

What initiates T cell signalling?

Answer 12

TCR recognition of peptide–MHC complexes

Question 13

What is LAT in T cells?

Answer 13

Linker for Activation of T cells – a scaffold protein forming the LAT signalosome

Question 14

What does the LAT signalosome do?

Answer 14

Organises multiple signalling proteins to amplify and control TCR signals

Question 15

What determines T cell subtype differentiation (e.g., Th1, Th2)?

Answer 15

Integration of TCR signals with cytokine signalling (e.g., IL-2, IL-12)

Question 16

What are signalosomes?

Answer 16

Modular multi-protein complexes that control timing, location, and intensity of signalling

Question 17

Why are signalosomes important?

Answer 17

They ensure specific, efficient, and controlled immune activation

Question 18

What prevents immune overactivation?

Answer 18

Co-receptors, inhibitory proteins, and threshold regulation

Question 19

Why is signalling regulation important?

Answer 19

To avoid autoimmunity, hyperinflammation, and immune exhaustion

Question 20

What do TLRs recognise?

Answer 20

PAMPs – pathogen-associated molecular patterns

Question 21

What pathways do TLRs activate?

Answer 21

• NF-κB
• IRFs
• MAPKs

Question 22

What are the outcomes of TLR signalling?

Answer 22

Production of inflammatory cytokines and type I interferons

Question 23

What signalling pathway do IFN receptors use?

Answer 23

The JAK-STAT pathway

Question 24

What genes do IFNs upregulate?

Answer 24

Interferon-stimulated genes (ISGs) – mediate antiviral effects and immune activation

Question 25

Do immune cells use unique or shared signalling pathways?

Answer 25

They use shared core pathways (e.g., JAK/STAT, MAPK), modulated for immune-specific functions

Question 26

What ensures immune signalling specificity?

Answer 26

Receptor types, scaffold proteins, co-receptors, and cell-specific gene expression