Immunology 7 Flashcards
(32 cards)
What is the approximate beta subunit of IL-2 receptor affinity for IL-2?
Moderate
After T cell activation what subunit in IL-2 receptor is expressed?
alpha, creating a trimeric receptors with higher affinity for IL-2
Does IL-2 act in a paracrine or autocrine or endocrine fashion?
ALL OF THE ABOVE!
However they are short range so only a few exhibit endocrine
Cytokines can exhibit pleitrophy. What is this?
These act on many different types of cells.
Give an example of of a cytokine that exhibits pleitrophy.
IL-4 which binds TNF-α receptor.
This is released by Th cells.
Causes differentiation in B cells and proliferation in other cells.
Name the four structurally distinct cytokine families.
Haematopoietins Interferons
Chemokines
TNF (tumour necrosis factor)
What do Haematopoitic cytokines do?
They support the growth and differentiation of haematopoietic cells.
What are the 5 structurally distinct cytokine receptors?
- Immunoglobulin super family receptors
- Class I cytokine receptors
- Class II cytokine receptors
- TNF receptors
- Chemokine receptors
What is the common signalling subunit in class 1 cytokine receptors?
The beta chain. This is involved in signal transduction. The other chain determines specificity of binding to cytokine.
How does receptor families having a common signalling chain help to explain cytokine redundancy?
Because cytokines can affect a very similar subunit with the same cascade.
What is the general model of signal transduction mediated by most class1 and class2 cytokine receptors?
JAK-STAT pathway
What are PAMPs?
Pathogen asssociated molecule patterns. commonly expressed by pathogens and bind to receptors in the innate immune system. Often result in cytokine release.
Bacterial LPS binds to what?
Either TLR4/TLR2. This drives production of IL-2 by dendritic cells.
What affect does IL-2 have on NK cells?
Causes production of interferon-gamma
What affect does interferon-gamma have on Naiive CD4+ T cells when they are activated in its presence (and the presence of IL-2)?
The cells is committed to differentiating into a Th1 cell.
Pathogens such as worms generate what kind of Th cell?
Th2 cell, driven by IL-4
PAMPs have been detctedin worms that drive Th2 cells.
When APC activates a CD4+ t cells and there is a lot of IFN-gamma in the environment, what will it become?
A Th1 cell, signalling by Stat1.
Drives production of IFN-gamma
When APC activates a CD4+ t cells and there is a lot of IL-4 in the environment, what will it become?
A Th2 cell driving production of IL-4
Do IFN-gamma and IL-4 antagonise each other?
Yes
What are Th1 cells effective against?
Bacteria/virus’
What are Th2 cells effective against?
Heminth parasites
What are the main cytokines that Th1 cells release?
IFN-gamma
TNF
IL-2
IL-12
What are the main cytokines that Th2 cells release?
IL-4
IL-5
IL-13
What s the effect of IFN-gamma?
Activates macrophages, induces B cell class switch to IgG3 (good at opsonizing bacteria & viruses & fixing complement)
