Innate Immunity: Nonspecific Defenses of the Host

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Lecture Slide Presentation prepared by Christine L. Case

M I C R O B I O L O G Ya n i n t r o d u c t i o n

ninth edition TORTORA FUNKE CASE

16Innate Immunity:

Nonspecific Defenses of the Host


TERMINOLOGY

Susceptibility: Lack of resistance to a disease.

Immunity: Ability to ward off disease.

Innate immunity: Defenses against any pathogen.

Adaptive immunity: Immunity, resistance to a specific

pathogen.


Host Defenses: OR WHAT WE ARE BORN WITH

Figure 16.1

OR THE ABILITY TO MAKE THEM


Physical Factors

Skin

Epidermis consists of tightly packed cells with

Keratin, a protective protein


Physical Factors

Mucous membranes Ciliary escalator:

Microbes trapped in mucus

are transported away from

the lungs. Lacrimal apparatus:

Washes eye. Saliva: Washes microbes off. Urine: Flows out. Vaginal secretions: Flow out.

Figure 16.4a


Chemical Factors

Fungistatic fatty acid in sebum.

Low pH (3-5) of skin.

Lysozyme in perspiration, tears, saliva, and tissue

fluids.

Low pH (1.2-3.0) of gastric juice.

Transferrins in blood find iron.


Normal Microbiota

Microbial antagonism/competitive exclusion: Normal

microbiota compete with pathogens.


Formed Elements in Blood

Table 16.1 (1 of 2)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 16.1 (2 of 2)

Formed Elements in Blood


Neutrophils 60-70%

Basophils 0.5-1%

Eosinophils 2-4%

Monocytes 3-8%

Lymphocytes 20-25%

Differential White Cell Count

Percentage of each type of white cell in a sample of

100 white blood cells.


White Blood Cells

Neutrophils: Phagocytic

Basophils: Produce histamine

Eosinophils: Toxic to parasites and some phagocytosis

Dendritic cells: Initiate adaptive immune response

Monocytes: Phagocytic as mature macrophages

Fixed macrophages in lungs, liver, and bronchi

Wandering macrophages roam tissues.

Lymphocytes: Involved in specific immunity.

PLAY Animation: Host Defenses


Phagocytosis

Phago: from Greek,

meaning eat

Cyte: from Greek,

meaning cell

Ingestion of microbes

or particles by a cell,

performed by

phagocytes.

Figure 16.6


Phagocytosis

Figure 16.7


Inhibit adherence: M protein, capsules

Streptococcus pyogenes, S. pneumoniae

Kill phagocytes: Leukocidins Staphylococcus aureus

Lyse phagocytes: Membrane attack complex

Listeriamonocytogenes

Escape phagosome Shigella

Prevent phagosome-lysosome fusion

HIV

Survive in phagolysosome Coxiella burnetti

Microbial Evasion of Phagocytosis

PLAY Animation: Phagocytosis


Inflammation

Redness Pain Heat Swelling (edema) Acute-phase proteins activated (complement, cytokine,

and kinins) Vasodilation (histamine, kinins, prostaglandins, and

leukotrienes) Margination and emigration of WBCs Tissue repair


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


Inflammation

Figure 16.8a–b


Inflammation

PLAY Animation: Inflammation

Figure 16.8c–d


Fever: Abnormally High Body Temperature

Hypothalamus normally set at 37°C.

Gram-negative endotoxin cause phagocytes to release

interleukin–1 (IL–1).

Hypothalamus releases prostaglandins that reset the

hypothalamus to a high temperature.

Body increases rate of metabolism and shivering which

raise temperature.

When IL–1 is eliminated, body temperature falls (crisis).


Fever

Advantages

Increase transferrins

Increase IL–1 activity

Disadvantages

Tachycardia

Acidosis

Dehydration


The Complement System

Serum proteins

activated in a

cascade.

Figure 16.9


Effects of Complement Activation

Opsonization or

immune adherence:

Enhanced

phagocytosis.

Membrane attack

complex: Cytolysis.

Attract phagocytes.

Figure 16.10


Effects of Complement Activation

Figure 16.11


Classical Pathway

Figure 16.12


Alternative Pathway

Figure 16.13


Some Bacteria Evade Complement

Capsules prevent C activation.

Surface lipid-carbohydrates prevent MAC formation.

Enzymatic digestion of C5a.

PLAY Animation: The Complement System


Interferons (IFNs)

Alpha IFN and Beta IFN: Cause cells to produce

antiviral proteins that inhibit viral replication.

Gamma IFN: Causes neutrophils and macrophages

to phagocytize bacteria.


Interferons (IFNs)

Figure 16.15


Innate Immunity

Transferrins

Bind serum iron

Antimicrobial peptides

Lyse bacterial cells

Documents

Innate Immunity: Nonspecific Defenses of the Host