Lectures 16 & 17: Cytokines & Chemokines Flashcards
What is the typical molecular weight of cytokines?
low (usually <30 kDa)
cytokines mediate effects via specific ___ on target cells
receptors
most cytokines are secreted, but some do exist in ____ forms and are active
membrane-bound
what is the structure of most cytokines? Are there any exceptions? well as some others
most are single polypeptide chains. Exception: aggregated forms like tumor necrosis factor (TNF) which is a heterodimer as well as some others
what makes the following cytokines different from the typical structure: IL-12, IL-23, IL-27, IL-35 and IL-39
they are heterodimers when most cytokines are monomeric
cytokines can have potent effects at ____ concentrations
picomolar
In general, what is the overarching function/role of cytokines?
to regulate the intensity and duration of immune response by stimulating or inhibiting activation, proliferation and or differentiation and migration of multiple cell types and by regulating the synthesis and secretion of Ig and other cytokines, or in some cases cell death in target cells
autocrine signalling
cytokine binds to receptors on the same cell that secreted it
paracrine signalling
cytokine binds to receptors on a nearby cell
juxtacrine signalling
cytokine binds to a neighbouring cells
endocrine cytokine signalling
cytokine binds to receptors on distant target cells
what is pleiotropy?
a cytokine has different effects on different target cells
what is redundancy?
different cytokines have the same effect on a target cells
what is a synergistic effect?
an effect greater than the additive effect of each cytokine alone
what is antagonistic effects of cytokines?
when two cytokines have opposing effects
what is a cascade effect with cytokines?
cytokine signalling that stimulates other cytokines, forming cytokine networks
Give 7 subclasses of cytokines
- lymphokines
- monokines
- chemokines
- interferons
- tumor necrosis factor
- colony stimulating factors
- interleukins
what are lymphokines?
cytokines secreted by lymphocytes
what are monokines?
cytokines secreted by monocytes and macrophages
what are chemokines?
cytokines with chemoattractant properties
what are interferons?
cytokines initially described as having anti-viral activity
give an example of a colony stimulating factor
GM-CSF
what are interleukins?
cytokines with a role in communication between leukocytes
how many interleukins have been described?
41