Cytokines and Cytokine Signaling Flashcards
Proteins that are synthesized and secreted in response to external stimuli
Cytokines
When one cytokine has different effects on many cell types it is called
Pleiotropic
When different cytokines have the same or overlapping effects, they are called
Redundant
May depend on time of exposure and concentration of cytokine
Pleiotropy
A cytokine can have different effects on different
Cell types
Cytokines acting on hepatocytes causes synthesis of acute phase
Proteins
Cytokines acting on osteoclasts causes
Bone Reabsorption
Cytokines acting on neutrophils causes increased adhesion to
Endothelium
Often based on historical accident of discovery (e.g., TNF)
Cytokine nomenclature
Generally, signals between WBCs
Interleukin (IL-n)
Play a role in development in formation of the immune system
–Stimulation of cell production, proliferation, differentiation
Cytokines
Cytokines also function in the day-to-day function of the immune system; targeting cells to immune tissues for formation and organization. I.e. cytokines function in
Homeostasis
Cytokines also function in response to
Infections and inflammation
What are the two major classes of cytokines?
- ) Cytokines
2. ) Chemokines
Generally soluble proteins, ≥18 kD (a few have membrane-bound forms)
-Signal through receptors coupled to protein kinases
Cytokines
Cytokines stimulate growth, differentiation, defensive capacity of
Immune system cells
Produce local and systemic manifestations of infection and disease
Cytokines
Smaller (8-10 kD) and signal through G-protein-coupled receptors (GPCRs)
Chemokines
Cytokines signal through
Protein kinases
Chemokines signal through
G-protein coupled receptors
Attract inflammatory and other effector cells to site of chemokine production; cellular activation; developmental targeting of cells to organs
Chemokines
Induced, and produced transiently, when and where needed
Cytokines
Unregulated or chronic production of cytokines can cause
Damage
Act through specific cell-surface receptor proteins
Cytokines
Binding of cytokines to receptors initiates intracellular signaling → changes (↑,↓) in
Transcription
Each cell type may undergo several types of changes; different cell types (or cells at different states of differentiation) respond according to their unique programming
-This is called
Pleiotropy
An example of a cytokine is Type I (III) interferons, which provide
Antiviral protection
Example of cytokines that function in inflamation
IL-1/TNF-α
Function in antiviral defense
Type I interferons
The gene clusters for type I interferons are located on chromosome
9
Are generally co-expressed
Type I interferons
What are the receptors for type I interferons?
IFNAR
Used to treat hepatitis B and C, and genital warts
IFN-α
IFN-β is used to treat
Multiple Sclerosis