INNATE AND ADAPTIVE IMMUNITY IMMUNE SYSTEM AND DISEASE.

INNATE AND ADAPTIVE IMMUNITY

IMMUNE SYSTEM AND DISEASE

MECHANISMS OF PATHOGENICITY

• Pathogenicity: The ability to cause • disease• Virulence: The extent of pathogenicity

PORTALS OF ENTRY• Mucous membranes• Skin• Blood• Respiratory tract• Gastrointestinal tract

MECHANISMS OF PATHOGENICITY

Figure 15.9

THE CONCEPT OF 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

AN OVERVIEW OF THE BODY’S DEFENSES

Figure 16.1

• Innate immunity: Defenses against any pathogen• Adaptive immunity: Induced resistance to a

specific pathogen

FIRST LINE OF DEFENSEINNATE (NON-SPECIF IC) IMMUNITY

PHYSICAL FACTORS

• Skin• Epidermis consists

of tightly packed cells with• Keratin, a protective

waterproof protein

Figure 16.2

• Mucous membranes• Mucus: Traps microbes• Ciliary escalator:

Microbes trapped in mucus are transported away from the lungs

CILIARY ESCALATOR

Figure 16.4

CILIARY ESCALATOR

Figure 24.7

PHYSICAL/CHEMICAL FACTORS

• Lacrimal apparatus: Washes eye

• Saliva: Washes microbes off

• Urine: Flows out• Vaginal

secretions: Flow out

CHEMICAL FACTORS

• Fungistatic fatty acid in sebum• Low pH (3–5) of skin• Lysozyme in perspiration, tears, saliva, and urine• Low pH (1.2–3.0) of gastric juice• Low pH (3–5) of vaginal secretions

GENETIC RESISTANCE

• Some individuals may have enough of a genetic difference that will allow them to be immune to a specific pathogen. • Ex: Humans carrying a gene for sickle-cell anemia are

immune to malaria!• Other examples: leprosy, tuberculosis (20% exposed are

resistant), certain fungal infections• Asymptomatic carriers – Herpes simplex

SECOND LINE OF DEFENSEINNATE (MAINLY NON-SPECIF IC)

Red Blood Cells Transport O2 and CO2

White Blood Cells:Neutrophils Phagocytosis

Basophiles Histamine

Eosinophils Kill parasites

FORMED ELEMENTS IN BLOOD

FUNCTION CELL MORPHOLOGY

FORMED ELEMENTS IN BLOOD

Monocytes Phagocytosis

Dendritic cells Phagocytosis

Natural killer cells Destroy target cells

FUNCTION CELL MORPHOLOGY

FORMED ELEMENTS IN BLOOD

T cells Cell-mediated immunity

B cells Produce antibodies

Platelets Blood clotting

FUNCTION CELL MORPHOLOGY

• Percentage of each type of white cell in a sample of 100 white blood cells

Neutrophils 60–70%

Basophils 0.5–1%

Eosinophils 2–4%

Monocytes 3–8%

Lymphocytes (T and B cells) 20–25%

DIFFERENTIAL WHITE CELL COUNT

DEVELOPMENT OF A MACROPHAGE

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

• Neutrophils• Fixed macrophages• Wandering macrophages VIDEO

Figure 16.7

PHAGOCYTOSIS

HOW DO WBC SURVEY AND RECOGNIZE?

• PRRs – Patten Recognition Receptors• Protein located on surface of WBC

• PAMPs – Pathogen Associated Molecular Pattern• Proteins, lipids, or carbs located on the pathogen that are

distinguishable from other non-pathogenic cells such as:• Peptidoglycan, lipoteichoic acid, lipopolysaccharides,

flagellin, zymosan, double stranded RNA, etc…

• Adherence

COMPONENTS OF LYMPHATIC SYSTEM

Figure 16.5a

MAJOR FUNCTIONS OF LYMPHATIC SYSTEM

• 1. Provide a route for the extracellular fluid to return back to the circulatory system

• 2. Acts a “drain off system” for inflammatory system

• 3. Involved in immune response by transporting numerous WBC (esp. T & B cell, and antibodies)

Imp differences from circulatory system:Lymph fluid travels only in ONE DIRECTION (extremities to

heart) Lymph is moved only by contraction of the skeletal muscles

THE LYMPHATIC SYSTEM

Figure 16.5b–c

INFLAMMATION

Identifiable signs of inflammation:• Redness (rubor)• Swelling (tumor)• Pain (dolor)• Warmth (calor)

• Acute-phase proteins activated (complement, cytokine, and kinins)

• Vasodilation (histamine, prostaglandins, and leukotrienes)

WHAT CAUSES AN INFLAMMATORY RESPONSE?

• Tissue injury or death (physical – bump, fall, etc..)• Trauma from infection• Allergic reactions (diet or environmental factors)

PRIMARY FUNCTION OF THE INFLAMMATORY RESPONSE

• 1. mobilize and attract immune response to site of injury

• 2. sets scene to repair tissue damage & clear away harmful substances

• 3. destroy and block microbes from further invasion

THE PROCESS OF INFLAMMATION

Figure 16.8a, b

PHAGOCYTE MIGRATION AND PHAGOCYTOSIS

Figure 16.8c

[Insert Animation Inflammation: Overview, Steps.]

FEVER

• Hypothalamus normally set at 37°C

• Toxins from bacteria trigger the deregulation of the hypothalamus (exogenous pyrogen). Examples are endotoxins (remember them?).• Pyrogen – substance that causes a rise in body temp

• Monocytes, neutrophils, and macrophages endogenous pyrogens as part of inflammatory response. (ex: macrophages -> interleukin 1 (IL-1) & tumor necrosis factor (TNF)).

• Vasodilation and sweating: Body temperature falls

FEVER

• Advantages• Inhibits multiplication of

temp sensitive microbes• Lower iron concentrations

(nutrient used by some microbes that can limit their growth)

• Speeds up immune response such as phagocytosis

• Produces Interferons

• Disadvantages• Tachycardia• Acidosis• Dehydration• 44–46°C fatal

INTERFERONS (IFNS)

• IFN- and IFN-: Cause cells to produce antiviral proteins that inhibit viral replication

• Gamma IFN: Causes neutrophils and macrophages to phagocytize bacteria

ANTIVIRAL ACTIONS OF INTERFERONS

Figure 16.15

IMMUNE CELL TYPES (AGAIN…)

Good site for review (click here)