Cytokines Flashcards
What are interleukines? (IL)
cytokines that are produced by leukocytes and act on leukocytes
What are chemokines? What do they do?
another group of molecules important in communication of leukocytes
- recruit and activate leukocytes
- regulation of leukocyte migration during homeostasis and inflammation
- selectively regulate adhesion process, chemotaxis, and activation of various populations and subpopulations of leukocytes
What is Chemotaxis?
a phenomenon in which cells move from an area of low chemical signal to an area of high chemical signal
What are the properties of cytokines?
- bind to their receptors on target cells thus initiate activating or suppressive signals
- have high affinity for their receptors. Low concentrations are enough to initiate cytokine signalling
What is autocrine signalling?
a substance produced by a cell binds to a receptor located on the same cell that produced it and activates the cell.
What is paracrine signalling?
a substance binds to a receptor found on a cell in the proximity of the producer cell
What is endocrine signalling?
a substance binds to a receptor found on a cell located in a distant part of the body.
Cytokines are able to perform what kinds of signalling?
- autocrine
- paracrine
- endocrine
What actions do cytokines have?
- pleiotropic action
- redundancy
- synergistic action
- antagonistic action
- cascade action
What is pleiotropic action of cytokines?
a given cytokine has different biological effects on different target cells
What is the redundancy of cytokines?
two or more cytokines exert the same biological effect on the same cells
What is the synergistic action of cytokines?
the effect of two cytokines on a particular cell is greater than the additive effect of individual cytokines
What is the antagonistic action of cytokines?
action of one cytokine inhibits the effect of another cytokine
What is the Cascade action of cytokines?
action of a cytokine leads to induction of one or more cytokines which in turn induce production of other cytokines
Cytokines act in an antigen-nonspecific manner. What does this mean?
cytokines will bind to any cell that expresses a cytokine receptor
What are the biological functions of cytokines?
- development of cellular and humoral immunity
- induction of inflammatory responses
- regulation of intensity and duration of immune response
- regulation of hematopoeisis
- regulation of proliferation and differentiation of cells
- wound healing
What cytokines are involved in innate immunity? What is their generalized function?
- Interleukin 1 (IL-1) - inflammation
- Tumor necrosis factor-a (TNF-a) - inflammation
- Interleukin 12 (IL-12) - influences adaptive immunity
- Interleukin 6 (IL-6) - influences adaptive immunity
- Interferon a (IFN-a) - antiviral state
- Interferon B (IFN-B) - antiviral state
What cytokines are involved in adaptive immunity? What is their generalized function?
- Interleukin 2 (IL-2) - T and B cell proliferation, NK activation and proliferation
- Transforming growth factor B (TGF-B) - inhibits proliferation of certain cells
- Interferon y (IFN-y) - activates macrophages and increases MHC expression and antigen presentation
What are the different groups of proteins that cytokines belong to?
- hematopoeitins
- interferons
- chemokines
- tumor necrosis factor family (TNF)
What are the four protein families that cytokine receptors belong to?
- Immunoglobulin superfamily receptors
- Class I cytokine receptors (hematopoietin)
- Class II cytokine receptors (interferon)
- TNF receptors
How many subunits are required for cytokine binding? How many subunits are required for signal transduction?
Binding - one
Signalling - one
What is the minimum number of subunits a cytokine receptor can have?
2
What is a common feature of subfamilies of class I cytokine receptors?
possession of an identical signalling subunit but different binding subunit
What are the subfamilies of class I cytokine receptors and what is their common subunit(s)?
- GM-CSF receptor subfamily (common B subunit)
- IL-6 receptor subfamily (common gp130 subunit)
- IL-2 receptor subfamily (common y subunit)
Tue or false? Possession of a common signalling subunit may explain why redundancy or antagonism is possible.
True
What are the actions of IL-3, IL-5, and GM-CSF?
- affect hematopoietic cells
- activate monocytes
- differentiation of megakariocytes
- induce proliferation of neutrophils
- induce degranulation of basophils to release histamine
What does possession of a single signalling subunit allow?
- elicitation of an identical signal by all involved cytokines
Why could posession of a common signalling subunit lead to antagonism?
- leads to antagonism because there is competition for the common subunit
