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University of Tabuk
Faculty of Applied Medical Science
Department of Medical Laboratory Technology
Basic Immunology
Mr.AYMAN.S.YOUSIF
MSc.Medical Microbiology &
Immunology
Academic Year: 1433-1434 (2012-2013)
Innate Immunity
Cytokines
Adaptive Immunity
Lecture 6:
Mr.AYMAN.S.YOUSIF
17- 18/03/2013
Objectives
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At the end of this lecture, you should be able to:
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Define the cytokines.
List the most important cytokines.
Know cytokines categories.
Understand the action manner of cytokines .
Understand the effects of cytokines .
Know cytokines receptor families.
Classify the cytokines based on the biologic actions .
Understand the biological function of the most
important cytokines .
What are cytokines?
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A group of low molecular weight polypeptides or
proteins or (glycoproteins) which are secreted by
activated immunocytes or some matrix cells and
possess high activity and various functions.
 Their major functions are to mediate and regulate
immune response and inflammatory reactions.
 Produced in response to microbes and other
antigen.
 Play an important role in both innate and adaptive
immunity.

Cytokine Names (Most Important Cytokines)
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 Interleukins
(IL) - produced exclusively by leukocytes.
 Lymphokines (LK) - produced by lymphocytes.
 Monokines (MK) - produced exclusively by monocytes.
 Interferon's (INF) - involved in antiviral responses.
 Colony Stimulating Factors (CSF) - support the growth
of cells.
 Chemokines - promote chemotaxis .
Cytokine Categories
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1.
TNF Family.
2.
Chemokine Family.
3.
Interferon Family.
4.
Hematopoietin Family.
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Cytokines Chemical Messengers of the
Immune Cells
Interleukins (IL) are cytokines that serve as
communicators between leukocytes.
According to the amino acid sequence Interleukins are
assigned numbers such as IL 1, etc..
Chemokines cause leukocytes to migrate to an infection
area.
Another family of cytokines is the Interferons.
Alpha interferon and IFNβ protect cells against viruses.
Gamma interferon (IFN) increases phagocytosis.
Tumor Necrosis Factor (TNF) promotes the
inflammatory reaction.
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

Cytokines Chemical Messengers of
the Immune Cells
Hematopoietic cytokines, function in controlling the
pathways by which stem cells develop into different red
or white cells.
Overproduction of cytokines leads to cytokines storm,
which results in tissue damage.
How do cytokines tell cells what to do?
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Produced by cells as part of normal cellular activity
and/or the result of environmental trigger (microbe).
Bind to receptors on (A cytokine acts only on a cell that
has a receptor for it). either cell which produced it or
another cell.
Receptor binding Trigger signal transduction pathways.
Signal results in altered pattern of gene expression .
Cytokines initiate their actions by binding to specific
membrane receptors on target cells.
Signal transduction pathway: The course by which a signal from
outside a cell is converted to a functional change within the cell.
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Result of environmental trigger
Hematopoietic cytokines
part of normal cellular activity
Cytokines can act in three different manners
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
Autocrine.
Cytokine binds to receptor on
cell that secreted it
 Paracrine.
Cytokine binds to receptors
on near by cells.
 Endocrine.
Cytokine binds cells in
distant parts of the body
The effects of cytokines (Cytokine Actions)
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
Pleiotropy.
Act on more than one cell type (IL 4).

Redundancy.
More than one cytokine can do the same thing (IL2, IL4, IL5).

Synergy.
Two or more cytokines cooperate to produce an effect that is
different or greater than the combined effect of the two cytokines
when functioning separately (IL-12 and IL-8) + (IFN and TNF)

Antagonism.
Two or more cytokines work against each other (IL-4 and IL-12)
+ (IFN and IL 10 ).
Cytokine Actions
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Five cytokine receptor families
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1. (Ig) Immunoglobulin superfamily receptors.
2. Class I cytokine receptor family(hematopoietin
receptors). Binds most of the cytokines in the
immune and hematopoietin systems.
3. Class II cytokine receptor family (interferon
receptors) .
4. TNF receptor family.
5. Chemokine receptor family.
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Cytokine receptors belong to families of receptor proteins, each with a
distinctive structure
Classification of Cytokines
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 Cytokines can be classified according to their principal
biologic actions to the following 3 groups, however many
of them mediate more than 1 of these functions:
1. Mediators and regulators of Innate Immunity :
 These are produced by activated MQ and NK cells in
response to microbial infections.
 They act mainly on endothelia cells and leukocytes to
stimulate the early inflammatory reaction to microbes.
 They include IL-1,6,10,12,15,18 TNFα, type l interferon
(INF-α and INF-β) and chemokines ( IL-8). IL1 ,6 and
chemokines are known as the proinflammatory ctyokines
Functional categories of Cytokines
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2- Mediators and regulators of Acquired immunity:
These are produced mainly by T cell in response to
specific recognition of foreign Ag.
 TH1 produce IL-2, INFγ and TNFβ
 TH2 produce IL-4,5,6,8,10,13
3- Stimulators of haematopoiesis:
 These are produced by bone marrow, stromal cells,
leukocytes, and other cells.
 They stimulate the growth and differentiation of
immature leukocytes.
 These include; stem cell factor, IL-3,7 and GM-CSF
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http://nfs.unipv.it/nfs/minf/dispense/immunology/lectures/files/immune_network.html
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Thank You