Basic Immunology

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Basic Immunology
University of Tabuk Faculty of Applied Medical
Science Department of Medical Laboratory
Technology
Mr.AYMAN.S.YOUSIF MSc.Medical Microbiology
Immunology
Academic Year 1433-1434 (2012-2013)
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Innate Immunity
Cytokines
Adaptive Immunity

• Mr.AYMAN.S.YOUSIF 17- 18/03/2013

Lecture 6
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Objectives

• At the end of this lecture, you should be able
  to
• 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 .

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What are cytokines?

• 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.

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Cytokine Names (Most Important Cytokines)

• 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 .

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Cytokine Categories

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 IFNß 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.

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How do cytokines tell cells what to do?

• 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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Hematopoietic cytokines

• Result of environmental trigger

• part of normal cellular activity

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Cytokines can act in three different manners

• 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

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The effects of cytokines (Cytokine Actions)

• 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 ).

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Cytokine Actions
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Five cytokine receptor families

• (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
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Classification of Cytokines

• 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
• 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 TNFa, type l
  interferon (INF-a and INF-ß) and chemokines (
  IL-8). IL1 ,6 and chemokines are known as the
  proinflammatory ctyokines

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Functional categories of Cytokines

• 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, INF? and TNFß
• 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/l
ectures/files/immune_network.html
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Thank You