This document summarizes the innate immune system. It describes the four types of defensive barriers: anatomic, physiologic, phagocytic, and inflammatory. The anatomic barriers include skin and mucous membranes. The physiologic barriers include low pH levels, chemicals that inhibit microbes, and fever. Phagocytic barriers involve white blood cells that ingest pathogens. The inflammatory response causes redness, pain, heat and swelling at sites of infection. Key cells that participate in innate immunity are also discussed.

1. INNATE IMMUNITY
Our Non-Specific Defenses
References:
1. Immunology by Kuby
2. Microbiology by Tortora
3. Essentials of Immunology by Roitt
Marilen M. Parungao-Balolong

2. WHAT YOU NEED TO KNOW
Differentiate innate from adaptive immunity
Define important terms related to innate
immunity
Be familiar with the 4 types of defense/
barriers in innate immunity
Be familiar with cells of the innate
immunity and their important roles

3. Innate vs Adaptive Immunity
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

4. Recall: the Lymphatic System
Q: Why do you
think your lymph
nodes swell when
there is infection?

5. 4 Types of Defensive Barriers in Innate Immunity
Anatomic/Physical
Physiologic
Phagocytic
Inflammatory

6. Anatomic: Skin
Serves as a Physical Barrier
Epidermis consists of tightly
packed cells with KERATIN, a
protective protein
Normal Microbiota:
Microbial antagonism/
competitive exclusion:
Normal microbiota
compete with pathogens

7. Anatomic:
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

8. SUMMARY: Skin & Mucous
Membranes

9. physiologic: low pH & Chemicals
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 (Bind Serum
iron)
NO inhibits ATP
production

10. Physiologic:
Temperature (FEVER)
Increased in 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)

11. Physiologic:
Temperature (FEVER)
Advantages
Increase transferrins
Increase IL–1 activity
Disadvantages
Tachycardia
Acidosis
Dehydration

12. Nice to
KNow:
Sickle Cell
Gene &
Malaria
Resistance

13. Differential White
Cell Count
1. Neutrophils: Phagocytic
2. Basophils: Produce histamine
3. Eosinophils: Toxic to parasites and some
phagocytosis
4. Dendritic cells: Initiate adaptive immune
response
5. Monocytes: Phagocytic as mature
macrophages
a. Fixed macrophages in lungs, liver,
and bronchi
b. Wandering macrophages roam
tissues
6. Lymphocytes: Involved in specific
immunity

14. To Be
Discussed
Fully in the
next Lecture :
Adaptive
Immunity

15. phagocytosis
Phago: from Greek, meaning
eat
Cyte: from Greek, meaning cell
Ingestion of microbes or
particles by a cell,
performed by phagocytes

16. Phagocytic
Barrier
*** PLay
Detailed Video

17. Who Can Evade This
Process...

18. Inflammatory
Barriers
Signs & Symptoms: Redness, Pain, Heat,
Swelling (edema)
Processes Involved
Acute-phase proteins activated (complement,
cytokine, and kinins)
Vasodilation (histamine, kinins, prostaglandins,
and leukotrienes)
Margination and emigration of WBCs
Tissue repair

19. What are Released?

20. Important Steps:
1. Tissue Damage
2. Vasodilation &
Increased Blood
Vessel
Permeability

21. 3. Migration
4. Tissue Repair
*** PLAY Detailed
Video

22. the complement system
Serum proteins activated in a cascade *** PLay
Detailed Video

23. alternative versus
classical
be Familiar with the
Similarities &
Differences...

24. the lectin pathway

25. Effects of Complement
Activation
Opsonization or
immune
adherence:
Enhanced
phagocytosis
Membrane attack
complex: Cytolysis
Attract phagocytes

26. Some Bacteria Can Evade
This Process...
How?
Capsules Prevent C Activation
Surface lipid-carbohydrates prevent
MAC formation
Enzymatic digestion of C5a

27. Interferons
Host-Cell Specific but not Virus Specific
SO HOW DOES IT STOP VIRUSES???
Alpha IFN and Beta IFN: Cause cells to produce antiviral
proteins that inhibit viral replication
Gamma IFN: Causes neutrophils and macrophages
to phagocytize bacteria

28. Interferons

29. To Summarize....

30. NEXT MEETING:
ADAPTIVE OR
ACQUIRED
IMMUNITY