Cytokines and Chemokines Flashcards
How are cytokines produced?
By lymphocytes
What makes an immune response possible?
Interaction between hematopoetic, lymphoid, and inflammatory cells
What were cytokines originally called?
Monokines or lymphokines
What activates and recruits leukocytes?
chemokines
True or False: Cytokines act in a non-specific manner
TRUE
Cytokines have _______ affinity for their receptors and ______ concentrations are needed to initiate cytokine signaling
HIGH affinity
low conc. enough to initiate cytokines
What actions do cytokines have to activate a cell?
- Autocrine action
- Paracrine action
- Endocrine action
What properties of cytokines allow them to regulate activity of immunocompetent cells in a coordinated manner?
- Pleiotropic action
- Redundant action
- Synergistic action
- Antagonistic action
- Cascade action
What is the pleiotropic action of cytokines?
When 1 cytokine exerts different effects on different target cells
IL-4 causes proliferation in Mast cells and Thymocytes, and causes activation, proliferation, and differentiation in B cells. This is an example of _____________
Pleiotropic action of cytokines
What is the redundant action of cytokines?
Give an example
When 2 or more cytokines exert the same effect on the same cell
Ex: IL-2 , IL-4 , and IL-5 all cause proliferation of B cells
What is the synergistic action of cytokines?
Give an example
When 2 cytokines team up to exert a greater effect on the target cell than if acting alone
Ex: IL-4 + IL-5 team up to induce class switching in B cells from IgM to IgE
What is the antagonistic action of cytokines?
Give an example
When the 1 cytokines inhibits another cytokine
Ex: IFN-y inhibits IL-4 , shuts down the response
How are growth factors expressed?
Constitutively
Is cytokine secretion short lived or long lived?
Short lived
What do cytokines help regulate?
Regulates..
- Hematopoesis
- Proliferation and differentiation of cells
- Would healing
- Induces inflamm. responses
What are the different groups of proteins that cytokines belong to?
- Hematopoeitins (Class 1 cytokine receptors)
- Interferons (Class 2 cytokine receptors)
- Chemokines
- Tumor necrosis factor (TNF)
How many subunits are required for cytokine binding?
How many subunits are required for signal transduction?
atleast 1 subunit for cytokine binding
2 subunits to signal transduction
What do Class I receptors possess?
- An identical signalling subunit (common Beta subunit)
- Different cytokine binding subunits
What happens if there is a defect in the common y chain on IL-2 receptors?
Associated with immunodeficiency
How many chains are found on the IL-2 receptor?
a, b, y chains
What are the different forms of the IL-2 receptor?
- Monomeric IL-2Ra - low affinity to IL-2
- Dimeric IL-2Rby - intermediate affinity for IL-2
- Trimeric IL-2Raby - high affinity for IL-2
Which receptor has the highest affinity for IL-2
Trimeric IL-2Raby receptor
(IL-2R alpha, beta, gamma receptor)
Cytokines with a second signaling subunit have a _______ affinity for the binding subunit
low
What explains how redundancy or antagonism is possible?
Common signaling subunit allows multiple cytokines to induce an identical signal
Which cytokines act in a redundant manner?
IL-3, IL-5, and GM-CSF
How can a common signaling subunit lead to antagonism?
Because cytokines are competing for the common subunit
What are chemokines?
small polypeptides that regulate adhesion, chemotaxis, and activation of leukocytes
Where are chemokines produced?
Lymphoid tissues, bone marrow, and other tissues like skin
What are the physiological functions of chemokines?
Wound healing
Angiogenesis
Develops brain + heart tissue
What cytokine induces secretion of chemokines?
IFN-a
C chemokines
1st 2 cysteins bound by disulphate bond
CC chemokines
1st 2 cysteins positioned 1 after the other
How many transmembrane domains do chemokines have?
7
What is the structure of a chemokine receptor?
- Extracellular domain for chemokine binding
- 7 transmembrane domains
- alpha, beta, gamma, intracellular domains ass. with G PROTEINS
Are there more chemokine receptors present on a T lymphocyte during resting or when activated?
Activated T lymphocyte has more chemokine receptors
What cells express CCR3 chemokine receptors?
Basophils and Eosinophils
What cells express CXR4 chemokine receptors?
resting and activated T cells, monocytes, and neutrophils
What are the most important oro-inflammatory cytokines?
TNF-a
IL-2
IL-6
IL-8
