1. INNATE HOST DEFENSES CHAPTER 16
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2. Host Defenses Innate Prior stimulation not needed (non-specific)
Often needed to trigger adaptive defenses
Adaptive
Respond after stimulation by the pathogen or agent (specific defenses, immune response)
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3. Types of Innate Defense
Physical Barriers
Chemical Barriers
Cellular Defenses
Inflammation Response
Fever Response
Molecular defenses
Interferon
Complement
Acute Phase proteins
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4. Barriers Physical Skin Stratified Close intercellular junctions
Waterproof, dead cells
Mucous membranes
Simple epithelium
Mucus layer
Mechanical defenses
Urine flow
Secretions
Chemical pH
Salt
Lysozyme
Transferrin
Serum
Lactoferrin
Saliva, milk, mucus
Defensins
Mucus and Extracellular fluid
Lyse microbial cells
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5. Cellular Defenses - Granulocytes
Basophils / Mast cells
Histamine release
Inflammatory response
Eosinophils
Modulate inflammation
Peroxide release
Neutrophils
Early phagocytic cells
Dendritic cells
Phagocytic
Antigen presenting cells, role in adaptive immunity
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

6. Cellular Defenses - Agranulocytes
Monocytes
Phagocytic cells
Later appearance than neutrophils
Lymphocytes
Cells of adaptive immunity
Will be discussed in Ch. 17
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

7. Cells Found in the Blood
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8. Phagocytosis Cells Involved: PMNs, macrophages, eosinophils
Order of appearance
Neutrophils first
Macrophages at the tail end
Eosinophil presence highest when worms and protozoa cause disease
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

9. Stages of Phagocytosis
Chemotaxis
Toll-like receptors on phagocytes (TLRs)
Recognition of microbial surface molecules
Cytokines, complement substances from damaged host cells
Adherence
Capsules, M proteins reduce this
Complement proteins enhance this
Ingestion
Formation of phagosome
Digestion
Phagosome + Lysosome = Phagolysosome
Formation inhibited by P. falciparum
Enzymes and reactive oxides damage microbes
Capsule protects microbes like Y. pestis
Staph. Strep. release WBC degrading toxins - Leukocidins
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10. Inflammation Cardinal Signs 3 Stages in acute Inflammation
Heat (calor)
Redness (rubor)
Pain (dolor)
Swelling (edema)
3 Stages in acute Inflammation
Vasodilation
Phagocytosos
Tissue Repair
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11. Chronic Inflammation Continuous pus formation, no drainage possible
Healing never achieved
Granulomatous tissue types:
Gummas (syphilis)
Tubercles (tuberculosis)
Lepromas (leprosy)
Steroidal anti-inflammatories can release microbes from granulomas
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12. Fever Response Benefits of Fever Systemic increase in body temperature
Risks for some patients
Convulsions, cardiac stress, dehydration may occur with v. high fevers
Pyrogens
Exogenous
Endogenous
Leukocyte Endogenous mediator
Reduced microbial growth
Toxin inactivation
Increased metabolism and immune cell responses
Increased phagocytosis
Interferon
Transferrin
Lysosomal activity
Rest for patient
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13. Molecular Defense: Interferons
Type I
IFN-α
IFN-β
Antiviral
Adjacent uninfected cells affected
Therapeutic Uses
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14. Complement System Serum proteins (10% by weight) Activation
Ag/Ab complexes (Classical)
Ag on pathogen surface (Alternate)
General functions
Enhanced inflammation
Opsonization
Cytolysis
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15. Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

16. Summary
Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.