Intro to Immunology

Question 1

What does the immune system do?

Answer 1

Identify and eliminates microorganisms and other harmful substances, as well as abnormal cancer cells

Question 2

How does the immune system work?

Answer 2

By distinguishing self and non-self molecules and/ or identifying danger signals (eg from acute inflammation)

Question 3

Why do we need a balanced immune system?

Answer 3

Optimal effectiveness so we have protection from pathogens (-ve reject donor tissue)

Question 4

What ways can we manipulate the immune system to prevent/treat disease?

Answer 4

Immunisation, anti-inflammatory and immunosuppressive drugs (eg aspirin/ibuprofen/cortisol steroids) and cancer immunotherapy

Question 5

What does immunotherapy do?

Answer 5

Enables the immune system to recognise, target and eliminate cancer cells - potential universal answer to cancer

Question 6

Why are tumours so deadly?

Answer 6

They secrete hormones that inactivate T-cells and so destroy immune response to foreign bodies

Question 7

What are the two branches of the immune system?

Answer 7

Innate and acquired immunity

Question 8

What is innate immunity composed of?

Answer 8

Natural/physical barriers, soluble factors (cytokines, acute phase proteins, inflammatory mediators and complement proteins) and immune cells (microphages, mast cells, natural killer cells and neutrophils)

Question 9

What is acquired immunity composed of?

Answer 9

Soluble factors (cytokines and antibodies) and immune cells (B and T cells)

Question 10

What is innate immunity?

Answer 10

A defines mechanism present continuously from birth and generally non-specific

Question 11

What is acquired immunity?

Answer 11

Induced by the presence of a foreign/non-self material. The response is usually unique to the specific pathogen

Question 12

What is the first line of defence against infection?

Answer 12

Natural/physical barriers (innate)

Question 13

How do pathogens enter the body?

Answer 13

Digestive system, respiratory system, urogenital system and skin damage

Question 14

How do pathogens attack the body?

Answer 14

Circulatory system and lymphatic system

Question 15

How does skin as a physical barrier work?

Answer 15

Composed of tightly packed, highly keratinised, multi layered cells that constantly undergo renewal and replacement

Question 16

What aspects of the skin help as physiological factors?

Answer 16

Low pH (5.5) and low oxygen tension

Question 17

What do glands in the skin secrete?

Answer 17

Sebaceous glands - secrete hydrophobic oils, lysozyme, ammonia and antimicrobial peptides

Question 18

What does secreted mucous do?

Answer 18

The mucous traps bacteria which are removed by ciliated cells

Question 19

Where do commensal bacteria live?

Answer 19

Epithelial surfaces - they have a symbiotic relationship with the host

Question 20

Where in the body is secreted mucous?

Answer 20

The membranes line all body cavities that come into contact with the environment (respiratory, GI and urogenital tract).

Question 21

What do protein pump inhibitors do?

Answer 21

Raise stomach pH

Question 22

What timeframe does innate response have?

Answer 22

Rapid (mins-hours)

Question 23

What timeframe does acquired response have?

Answer 23

Slow (days)

Question 24

What happens if innate and acquired don’t work together?

Answer 24

Most probably death

Question 25

What are the major functions of macrophages?

Answer 25

Phagocytosis, pro/anti-inflammatory, bacterial killing mechanisms, antigen presentation and wound healing/tissue repair

Question 26

Where are macrophages found?

Answer 26

Pretty much everywhere in the body - name changes dependent on location

Question 27

What are the major functions of mast cells?

Answer 27

Pro-inflammatory, parasitic killing machines and also linked to allergy and asthma

Question 28

What happens when physical barriers are breached?

Answer 28

Pathogens invade, innate immune responses initiated (phagocytes - macrophages and dendritic cells, and mast cells)

Question 29

How does pinocytosis work?

Answer 29

Ingestion of fluid surrounding cells

Question 30

How does receptor-mediated endocytosis work?

Answer 30

Molecules bound to membrane receptors internalised

Question 31

What is phagocytosis?

Answer 31

Intact particles are ingested whole - facilitated by opsonisation (look at lecture diagram for the how)

Question 32

How does phagocytosis work?

Answer 32

Macrophages express a set of ‘PRRs’
Receptors on macrophage surface binding to ‘PAMPs’ single formation of a phagocytic cup
Cup extends around target and pinches off - forms a phagosome
Fusion with lysosome. - phagolysosome (kills pathogens and degrades the contents)
Debris (including antigens) is released into extracellular fluid
Pathogen-derived particles are expressed on special cell surface receptors (MHC-II molecules)
Pro-inflammatory mediators are released (TNF-a)

Question 33

What is opsonisation?

Answer 33

The coating of pathogens by soluble factors (opsonins) to enhance phagocytosis

Question 34

How do mast cells work?

Answer 34

Degranulation then gene expression

Question 35

What is mast cell degranulation?

Answer 35

Release of pre-formed pro-inflammatory substances - toxic to pathogens

Question 36

What is mast cell gene expression?

Answer 36

Production of new pro-inflammatory substances

Question 37

What are some examples of pro-inflammatory mediators?

Answer 37

Nitric oxide, prostaglandins/leukotrienes, histamines and pro-inflammatory cytokines (TNF-a)