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Innate Immunity: NonspecificDefenses of the Host
Chapter 16
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I M M U N I T Y
1. Innate Immunity
2. Adaptive Immunity
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Figure 16.1
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F irst-line Defenses
1. Physical Bar riers
Skin, Mucous Membrane
2. Antimicrobial Substances
Lysozyme: tears,saliva
Lac
tofe
rr ins
and Trans
fe
rr ins
Defensins
Peroxidase
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F irst-line Defenses
3. Normal F lora
Competitive Exclusion
Production of toxins
Alte
ration of Environme
nt
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Cells of the Immune System
Hematopoietic Stem cell
Blood cells:
RB Cs
plate
le
ts
W B Cs
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W B Cs/Leukocytes
1. Granulocytes
Neutrophils
Eosinophils
Basophils
2.
Mononuc
le
ar phagoc
ytes
Macrophages
Dendriticcells
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Formed Elements in Blood
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W B Cs/Leukocytes
3. Lymphocytes
T and B lymphocytes
Professional Phagocytes???
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Formed Elements in Blood
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8)6/33% 4"',06/)#$(2A',2/%
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Percentage of each type of white cell in a sampleof 100 white blood cells
Neutrophils 6070%
Basophils 0.51%
Eosinophils 24%
Monocytes 38%
Lymphocytes 2025%
Differential White Cell Count
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Phagocytosis
Process of Phagocytosis:
1. Chemotaxis
2. Recognition and attachment
3. Engulfment: phagosome
4.
Formation of a phagolys
os
ome
5. Digestion
6. Exocytosis
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Figure 16.7
Phagocytosis
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The Concept of Immunity
Host Toll-like receptors ( T L Rs) attach to Pathogen-associated molecular patterns
(P A MPs)
TLRs induce cytokinesthat regulate the intensityand duration of immune responses
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Inhibit adherence: M protein,
capsules
Streptococcus pyogenes, S. pneumoniae
Kill phagocytes: Leukocidins Staphylococcus aureus
Lyse phagocytes: Membrane
attack complex
Listeria monocytogenes
Escape phagosome Shigella, Rickettsia
Prevent phagosome-lysosome
fusion
HIV, Mycobacterium tuberculosis
Survive in phagolysosome Coxiella burnettii
Microbial Evasion of Phagocytosis
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Inflammation
1. Local Response
2. Symptoms :
Redness: Rubor
Heat: Calor
Pain: DolorSwelling: Edema
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Inflammation
3. Causes:
4. Function:
Destroy injurious agent
L imit the
s
pre
adRepair damaged tissue
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Process of Inflammation
1. Trigger
2. Vasodilation and increasedpermeability of blood vessels
3. Phagocyte migration (Diapedesis)andphagocytosis(PM N vs. macrophages)
4. Tissue Repair
Pus formation
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Histamine Vasodilation, increased permeability
of blood vessels
Kinins Vasodilation, increased permeability
of blood vessels
Prostaglandins Intensity histamine and kinin effect
Leukotrienes Increased permeability of blood vessels,
phagocytic attachment
Chemicals Released by Damaged
Cells
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The Process of Inflammation
Figure 16.8a, b
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Phagocyte Migration and Phagocytosis
Figure 16.8c
[Insert Animation Inflammation: Overview, Steps.]
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Tissue Repair
Figure 16.8d
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Fever
1. systemic response to an infection
2. What causes?
Macrophages-I L1 hypothalamus
3. How is host helped?
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I N T E R F E R O N S
1. Who produces?
2. What are they and how do they act?
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Interferons (IFNs)
I F N- and I F N- : Causecells to produceantivir al proteins that inhibit viral replication
Gamma I F N: Causes neutrophils andmacrophages to phagocytize bacter ia
nt v ra ct ons o nter erons
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nt v ra ct ons o nter erons(IFNs)
Figure 16.15
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The Complement System
1. What is it?
2. Activated in three different ways
-Classical Pathway
-Lectin Pathway
-Alternative Pathway
l i l h f l i i
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Classical Pathway of Complement Activation
Figure 16.12
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Consequences of complement
activation1. Opsonization: C3b is an opsonin
2. Inflammation: C3a and C5a
3. Cytolysis: Membrane Attack Complex
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The Complement System
Figure 16.9
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The Complement System
C3b causes opsonization C3a + C5a cause inflammation
C5b + C6 + C7 + C8 + C9 cause cell lysis
I fl ti Sti l t d b
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Inflammation Stimulated by
Complement
Figure 16.11
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Some Bacteria Evade Complement
Capsules prevent C activation Surface lipid-carbohydrates prevent membrane
attack complex (MAC) formation
Enzymatic digestion of C5a