10 Cytokines Flashcards
(64 cards)
what are cytokines
Secreted proteins that regulate the amplitude and duration of immune and inflammatory responses
where and how are cytokines usually produced
Usually produced transiently and locally
what are cytokines like
Extremely potent
what do cytokines bind to
Bind to specific cell-surface receptors
effect of cytokine
Change cell behaviour (signal into cell and cause change)
what are the normal levels of cytokine used for
health
what are the increasing levels of cytokine used for
At increasing levels important for disease conditions e.g. toxic shock, sepsis and organ failure
why are cytokines so important
They regulate all the important biological processes
Cytokine action
Cytokine receptors made of at least two chains, cytoplasmic domains of which bind JAKs Cytokine binding dimerizes receptor, bringing together cytoplasmic JAKs, activate each other and phosphorylate receptor Transcription factors (STATs) binds to phosphorylated receptors, in turn phosphorylated by activated JAKs Phosphorylated STATs form dimers that move into nucleus to initiate gene transcription
GF
growth factors
CSF
colony stimulating factors
Cytokine families
Hematopoietin family
TNF family
Interferon family
Chemokine family
Hematopoietins cytokine family
Small proteins, interact with its own dimeric receptor, only when all together does it signal to cell that it’s found e.g. IL-4
class 1 cytokine receptor (hematopoietin-receptor family) - IL-3, IL-5 and GM-CSF
share a common beta receptor chain and the alpha chain is different in each case
class 1 cytokine receptor (hematopoietin-receptor family) - IL-2, IL-4. IL-7. IL-9 and IL-15
have a common gamma chain, beta chain differs for each receptor. IL-2 has a third chain, high-affinity subunit IL-2R alpha (CD25)
class 1 cytokine receptor (hematopoietin-receptor family)
just have alpha or beta receptors for erythropoietin, growth hormone and IL-13
IL-2 actions
Essential role in promoting T cell division and release of mediators
Also potentiates B cell growth
Activation of NK and monocytes so is important in amplifying immune response
IL-2 production
It is produced by Th cells
TNF cytokine family
TNF-alpha
TNF-beta
how do TNF cytokine family naturally occur
Ribbon representation of TNF family cytokines - they occur naturally as trimers (TOP)
what is the monomeric TNF bound to
Monomeric TNF bound to one subunit of TNF receptor (BOTTOM)
what group of receptors are TNF receptor in
Tnf receptors are members of large group of G protein coupled receptors
Cell activation by TNF
TNF trimer binds to TNF receptor when it comes together it has a conformational change turn signalling on inside the cell
Can go down multiple routes and turn on different routes in the cell
Can lead to lead to gene activation and apoptosis
Actions of TNF
- activates macrophages, help with defense against intracellular pathogens
- induces adhesion molecules on endothelial
- Promthromobitc actions means can help cause blood clotting
- growth factor for many cells
- can also cause production of other cytokines to be produced
- Importantly regulates haematopoiesis
