INNATE IMMUNITYOur Non-Specific Defenses

References:1. Immunology by Kuby

2. Microbiology by Tortora3. Essentials of Immunology by Roitt

Marilen M. Parungao-Balolong

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

Innate vs Adaptive ImmunitySusceptibility: 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

Recall: the Lymphatic System

Q: Why do you think your lymph nodes swell when there is infection?

4 Types of Defensive Barriers in Innate Immunity

Anatomic/Physical

Physiologic

Phagocytic

Inflammatory

Anatomic: SkinServes 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

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

SUMMARY: Skin & Mucous Membranes

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

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)

Physiologic: Temperature (FEVER)Advantages

Increase transferrins

Increase IL–1 activity

Disadvantages

Tachycardia

Acidosis

Dehydration

Nice to KNow:

Sickle Cell Gene & Malaria

Resistance

Differential White Cell Count

1. Neutrophils: Phagocytic2. Basophils: Produce histamine3. Eosinophils: Toxic to parasites and some

phagocytosis4. Dendritic cells: Initiate adaptive immune

response5. Monocytes: Phagocytic as mature

macrophagesa. Fixed macrophages in lungs, liver,

and bronchib. Wandering macrophages roam

tissues6. Lymphocytes: Involved in specific

immunity

To Be Discussed

Fully in the next Lecture :

Adaptive Immunity

phagocytosis

Phago: from Greek, meaning eat

Cyte: from Greek, meaning cell

Ingestion of microbes or particles by a cell, performed by phagocytes

Phagocytic Barrier

*** PLay Detailed Video

Who Can Evade This Process...

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

What are Released?

Important Steps:1. Tissue Damage2. Vasodilation & Increased Blood

Vessel Permeability

3. Migration4. Tissue Repair

*** PLAY Detailed Video

the complement system

Serum proteins activated in a cascade *** PLay Detailed Video

alternative versus classical

be Familiar with the Similarities & Differences...

the lectin pathway

Effects of Complement Activation

Opsonization or immune adherence: Enhanced phagocytosis

Membrane attack complex: Cytolysis

Attract phagocytes

Some Bacteria Can Evade This Process...

How?

Capsules Prevent C Activation

Surface lipid-carbohydrates prevent MAC formation

Enzymatic digestion of C5a

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

Interferons

To Summarize....

NEXT MEETING: ADAPTIVE OR

ACQUIRED IMMUNITY