Intro to Immunology (Week 2 Lecture 3)

Question 1

When did immunity first start being studied?

Answer 1

study began in the late 18th century with small pox outbreak (‘protection from diseases’)

Question 2

What is immunity?

Answer 2

host’s defense against destructive forces from outside and within the body
* A versatile and coordinated defense system.
* Recognition (of something foreign) and Response (attack back)

Question 3

Role of the immune system

Answer 3

• Defense against infection.
• Defense against tumors (can induce their own immune response)
• Recognition of newly introduced molecules (proteins, transplants).
• Source of inflammation (part of healing, inflammatory disease or autoimmunity).

Question 4

What are the two immune responses?

Answer 4

• innate
• acquired

Question 5

innate immune response

Answer 5

First immune response from birth which doesnt need to what the invading thing is to work effectively
* First response
* Immediate response
* Short term
* Non-specific (viruses, bacteria, etc.)
* Directs and initiates adaptive response

Question 6

Acquired (adaptive) immune response

Answer 6

Aquiring the immunity is based on the characterisitics of what the infection is
* Second response
* Delayed response (days)
* Long term
* Requires exposure
* Has memory
* Specific and selective

Question 7

Types of innate immunity

Answer 7

• anatomic barriers
• physiological barriers
• eating cells
• other cells

Question 8

anatomical barriers

Answer 8

• Skin
• Mucous membranes
• GI and respiratory tract (eat and breath in many toxins)

Question 9

physiological barriers

Answer 9

• Fever (growth inhibition)
• Low pH (Stomach)
• Chemical mediators

Question 10

Eating cells

Answer 10

Phagocytes/ Endocytes are recruited to sites of infection where they recognize foreign molecule and ingest it (intracellular killing)
* Monocytes/Macrophages
* Neutrophils.

Question 11

other cells (innate)

Answer 11

• Dendritic cells, mast cells: Recruited to sites of infection, recognize and engulf
• Natural Killers: surveillance/ killing/ transformed “self” cells (important for tumour surveillance to recognize self cells that have mutated)

Question 12

Types of adaptive immunity

Answer 12

• cell mediated immunity
• humoral immunity

Question 13

cell mediated immunity

Answer 13

Uses T-cells which are a type of white blood cell called lymphocytes. They help your immune system fight germs and protect you from disease.
* CD4 helper cells
* CD8 cytotoxic cells

Question 14

CD4 helper cells

Answer 14

Help coordinate the immune response by stimulating other immune cells, such as macrophages, B lymphocytes (B cells), and CD8 T lymphocytes (CD8 cells), to fight infection.
* 5 subsets of CD4 cells (Th1, Th2, Th17, Treg and Tfh)
* IL-2, IFN- g cytokines (messengers between cells)
* targets intracellular bacteria

Question 15

CD8 cytotoxic killer cells

Answer 15

Can directly kill cells harbouring pathogens, such as viruses
* TC1/ TC2 cells
* IL-4, IL-5, IL-10 cytokines (messengers between cells)
* extracellular bacteria antibody production

Question 16

humoral immunity

Answer 16

Produces B cells which make antibodies to eliminate/ neutralize microbes outside the normal cell
* deals with antigens from pathogens that are freely circulating, or outside the infected cells.

Question 17

Organs involved in the immune system

Answer 17

• Bone marrow: Origin and development (hence B cells)
• Thymus and Spleen, GI tract: Education and selection
• Lymph nodes: Reservoirs, circulation and traps
• Lymphatic vessels, blood vessels: transportation

Question 18

Effect of nutrition on the immune system

Answer 18

One of the most sensitive systems in the body to changes in nutritional status
* measures of immune function are used to assess nutritional status

Question 19

What is the leading cause of immunodeficiency worldwide?

Answer 19

protein energy malnutrition

Question 20

futile cycle of immunity and poor nutrition

Answer 20

Question 21

Continuum of Immune Responses

Answer 21

need a balance of:
* cytokines: innate (IL-2, IFN- g) and adaptive (IL-4, IL-5, IL-10)
* eicosanoids, oxylipids
* hormones (corticosteroids/stress)
* other mediators

Question 22

The good of inflammation

Answer 22

Inflammation is essential for normal defense against pathogens and repair of tissue damage
* Redness, heat, swelling and pain
* Keeps us alive
* Means immune system is working effectively

Question 23

The bad of inflammation

Answer 23

sustained inflammation disrupts metabolic pathways and suppresses immune response:
* Excessive tissue damage
* Induce insulin resistance by disrupting insulin signalling
* Impair ability to defend against future infection

Question 24

Acute inflammation

Answer 24

Healing of tissue
* Immediate defense to tissue damage/injury
* Usually < 3 wks
* Neutrophils recruited to site
* Variable systemic effects
* Not necessarily associated with tissue destruction
* Followed by healing and repair
* Inflammation resolves

Question 25

Chronic inflammation

Answer 25

Low grade inflammation is constantly on and production can be disruptive systemically
* Excessive activation and/or insufficiently regulated immune system
* Sustained duration
* Macrophages, T-lymphocytes & their mediators predominate
* Significant tissue damage
* Systemic effects

Question 26

Commonly Measured Mediators

Answer 26

• Glucocorticoid (stress hormones)
• Interleukin-6 (IL-6)
• Tumor Necrosis Factor (TNF-α)
• Interleukin-1 (IL-1)
• Interleukin-8 (IL-8)
• Eicosanoids (prostaglandins)

Bolded are pro inflammatory

Question 27

Metabolic changes with chronic inflammation (tumor)

Answer 27

• Liver (center of metabolism): ↑ Acute phase, ↓drug metabolism
• Muscle: ↑ proteolysis, ↓ synthesis
• Hypothalamus: ↓ appetite, ↑ sympathetic activity, ↑ REE, ↑ cortisol, ↓ testosterone
• Gut: early satiety
• produces C-reactive protein (non-specific)
• Fat: ↑ lipolysis, ↓lipoprotein lipase
• Brain: depression