IRCelular11 (stu)
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Transcript of IRCelular11 (stu)
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Objectives
After working through this module, you should
be able to:
Explain the mechanisms involved in cellular
immunity.
Explain the interaction between the
components of the immune system in regulating
immune response.
Describe the mechanism of immune response
towards superantigen
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Cellular Immune Response
While humoral immune response is for
extracellular bacterial, cellular immune
response is more for intracellular bacteria,
viruses, tumours and transplants.
Cells involved in specific cellular immune
response are the T lymphocytes
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Lymphocyte ActivationMacrophage
NK cell
TH2TH1
IFN-
IL-12IFN-
Il-12, TNF-
IFN-
Il-4, IL-10
Cross-regulation
Promotes cellular immunity Promotes humoral immunity
IL-4
IL-5IL-6
IL-10
IL-13
IL-2
IFN-TNF-
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Antigen Elimination
The elimination ofantigens in the effector phase ofspecific immune responses occurs by the cooperativeactions of differentiated lymphocytes and defence
mechanisms of innate immunity
In cell-mediated immunity, activated T lymphocytessecrete cytokines, which enhance the functions of
phagocytes and other inflammatory leukocytes
However, cytotoxic T cells do not require other
cooperating mechanisms to eradicate microbes
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Antigen Elimination
Cellular Immunity
Microbe (bacteria)surviving in phagocyte
MHC-II
CD4 recognizesexogenous antigen
Activation of microbicidalfunctions of phagocyte
MHC-I
CD8 recognizes
endogenous antigen Lysis of infected cell
Microbe (virus) infecting
non-phagocytic cell
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Regulation of Immune Response
The immune response has to be regulated and
brought back to the normal status as excessiveresponse will be detrimental to the body.
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Immunoregulation
Y Y Y
Y Y Y
Antigen
Macrophage IL-1
Suppresor T cell
IL-2
IL-1
Helper T cellStimulation
B cell
Feedback
inhibition
Idiotype network
interactions
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Regulation of Immune Response
Based on the diagram above, themechanisms of immunoregulation.
1.Control by antigen
level of exogenous antigen intensityof response
2.Feedback control by antibodyIgG inhibit responses via Fc receptor on
B-cells
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Regulation of Immune Response
3. T-cell regulation
a. activated T-cells express Fas and FasL
which restrain unlimited clonal expansion
Fas-mediated apoptosis of activatedmature cells
b. mutual inhibition between TH1 and TH2cells suppression
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Regulation of Immune Response
4. Idiotype networks
antigen-specific receptors on lymphocytes
can interact with the idiotypes on thereceptors of other lymphocytes to form anetwork (Jerne)
5. Genetic factors
10 genes control overall antibody response
affecting
- macrophage ag processing
- microbicidal activity
- rate of proliferation of differentiating
B-cells
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Regulation of Immune Response
6. Immunoneuroendocrine networks
- interaction among immunologic, neurologic
and endocrinologic systems
- regulatory interdependent circuits feedback by cytokines augmentingproduction of corticosteroids shutsdown TH1 and macrophage activity
- estrogens largely responsible for the moreactive responses in females relative to
males
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Regulation of Immune Response
7. Effects of diet and other factors on
immunity
- protein-calorie malnutrition impairs
- exercise
- trauma
- age: IL-2, TNF, IL-1, IL-6
- environmental pollution
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SUPERANTIGEN
ACTIVITY 1
Based on the diagrams below, how is
superantigen different from normal antigenin antigen recognition and stimulating animmune response?
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macrophage
lymphocytelymphocyte
macrophage
antigen
TCR TCR
Antigen piece
MHC II MHC II
ANTIGEN SUPERANTIGEN
V V V V
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References
Stites DP, Terr Al and Parslow TG. Medical Immunology. 10th Edition,Appleton & Lange, Prentice-hall International Inc. 2001.
Roitt I, Brostoff J and Male D. Immunology. 6th Edition, GowerMedical Publishing, London. 2001
Geo.F.Brooks, Janet S.Butel and Stephen A.Morse. Jawetz, Melnick,
& Adelbergs Medical Microbiology. 23rd Edition, McGraw-Hill. 2004.
Cedric Mims, Hazel M. Dockrell, Richard V.Goering, Ivan Roitt, DerekWakelin and Mark Zuckerman. Medical Microbiology. 3rd Edition,Elsevier Mosby. 2004.
Marjorie Kelly Cowan and Kathleen Park Talaro. Microbiology ASystems Approach. McGraw-Hill. 2006.