12 - Cytokines Flashcards
General CYTOKINE Traits
Are NOT stored
are rapidly synthesized & secreted after stimulation
Cellular Responses consist of:
Changes in GENE EXPRESSION
VVV
New Functions / PROLIFERATION of target cell
- EXCEPTIONS:*
- *Chemokines / TNF**
Which CYTOKINES do NOT result in
New Functions or Proliferation
after gene expression?
CHEMOKINES
induce motility
TNF
induce apoptosis
do NOT need activation of NEW PROTEINS
SUFFICICIENT ON THEIR OWN
Regulation of Cytokines
QUANITITY of cytokine Produced
EXPRESSION** or **DOWN-REGULATION
of Cytokine Receptors
Low Affinity Receptors
are found on MOST CELLS, in LOW QUANTITY
High Affinity Receptors
are expressed on ANTIGEN ACTIVATED cells
3 Types of CYTOKINE action
Autocrine
Act on SELF
Paracrine
Acts on NEARBY cell
Endocrine
Passes through CIRCULATION –> DISTANT CELL
IL-2 DOES ALL 3
What is PLEIOTROPY?
Pleiotropy
ONE CYTOKINE can act on MULTIPLE CELL TYPES
DIFFERENTLY
What is REDUNDANCY?
Redundency
MULTIPLE CYTOKINES
have the
SAME EFFECT** & use the **SAME SIGNALING SUBUNITS
Synergy / Antagonism
properties of Cytokines
Synergy
cytokines act together –> induce something
- *Antagonism**
- another cytokine** –> *_antagonizes action of another_
How do we CLASSIFY CYTOKINES?
BY THEIR ACTION
Functional Classification of Cytokines
Mediators & Regulators of INNATE & ADAPTIVE IMMUNITY
Stimulators of Hematopoeiesis
Chemokines
What are the PRIMARY PRODUCERS of
Cytokines of the INNATE IMMUNE SYSTEM?
MONONUCLEAR PHAGOCYTES
Dendritic Cells + Macrophages
Also by,
Endothelial + Epithelial Cells
What do these cytokines MEDIATE & REGULATE?
TNF-A
IL-1 // IL-10 // IL-12
INF-A + INF-B
Chemokines
INNATE IMMUNE SYSTEM
Produced primarily by:
Mononuclear Phagocytes = Dendritic cells + Macrophages
Which Cytokine?
Mediator of ACUTE INFLAMMATORY RESPONSE
to GRAM (-) Bacteria & other microbes
Induces INFLAMMATION
in an effor to limit spread of infection
Responsible for many
systemic complications of severe INFECTION
TNF-A
Mediator & Regulator of INNATE IMMUNITY
Low Quantities of TNF-A cause what?
TNF-A Biologic Actions
LOCAL INFLAMMATION
Neutrophil Activation –> Chemokine Production
Endothelial cells activated to
secrete chemokines + adhesion molecules
some Apoptosis
Increased Vascular permeability / Redness / Swellin
Inflammation
MODERATE Quantities of TNF-A cause what?
TNF-A Biologic Actions
SYSTEMIC EFFECTS
Brain –> produces FEVER
Hepatocytes produce Acute Phase Proteins
Bone marrow leukocyte production is increased
HIGH QUANTITIES of TNF-A cause what?
TNF-A Biologic Actions
SEPTIC SHOCK
Heart -> low output due to inhibition of myocardial contractility
Vascular endothelium
HypoGlycemia
Which Cytokine?
Pro-Inflammatory with TNF-Alpha
@Low Concentrations
local inflammation
@HIGH concentrations
Pyrogen / Cachexia / Acute Phase Proteins Secreted
IL-1
Secreted by Activated Macrophages
Mediator & Regulator of INNATE IMMUNITY
- *IL-1 + TNF-A**
- *Functions Together**
Mediator & Regulator of INNATE IMMUNITY
they make ENDOTHELIAL CELLS:
- *LEAKY to fluids**
- -> influx of plasma w/ AB’s
- *STICKY for leukocytes**
- -> influx of neutrophils –> monoctes/lymphocytes
DIFFERENCES between IL-1 and TNF-A
Mediator & Regulator of INNATE IMMUNITY
IL-1
cannot cause cell APOPTOSIS
cannot cause SHOCK by itself
binds DIFFERENT RECEPTOR, but produces a similar effect
What Cytokine?
INDUCER of ADAPTIVE Immune response
VVV
Stimulates DIFFERENTIATION of
Th -> Th1 (produce INF-y) –> macrophage activation
&
Enhances Cytolytic fxn of Activated CD8+ T-cells
–> LYSIS of infected cell
Principle mediator of:
EARLY INNATE IMMUNE RESPONSE
IL-12
Th –> Th1 producing TNF-y
macrophage activation -> kill phagocytosed microes
Enhance CD8+ Tc
lysis of infected cell
from activated macrophages + dendritic cells
Mediator & Regulator of INNATE IMMUNITY
What Cytokine?
INHIBITOR of host immune responsed involving macrophages
INHIBITS Cellular Immunity
in favor of HUMORAL RESPONSE
INHIBITS production of IL-2** & **TNF-a
by activated macrophages
INHIBITS expression of Costimulators** & **MHC
by macrophages
IL-10
From
Th2 cells + late stage macrophages
Mediator & Regulator of INNATE IMMUNITY
What Cytokine?
Interfere with VIRAL REPLICATION
response to dsRNA
LEUKOCYTE INTERFERON
Major source is
Mononuclear Phagocytes & Viral-Infected Cells
INF-a
Mediator & Regulator of INNATE IMMUNITY