IH2

Question 1

What is the main function of the immune system?

Answer 1

1. Recognition (presence of non-self e.g. pathogen) (significant to organ donation, also immune system doesn’t attack commensal bacteria)
2. Effector function (contain/eradicate infection)
3. Regulation (appropriate & measured response)
4. Memory (immediate & stronger response on second exposure) (the whole basis of vaccination)

Question 2

Describe the following for the recognition mechanism of the innate immunity:

1) speed of response
2) variance in the way they respond
3) specificity
4) effectiveness of response

Answer 2

1) rapid
2) fixed
3) limited number of specificities
4) constant

Question 3

Describe the following for the recognition mechanism of the adaptive immunity:

1) speed of response
2) variance in the way they respond
3) specificity
4) effectiveness of response

Answer 3

1) slow (days to weeks)
2) variable
3) numerous highly selective specificities
4) improve during response

Question 4

What does the innate and adaptive response have in common?

Answer 4

the mechanism for the destruction of pathogens e.g. neutrophils engulf pathogens while B cells selectively engulf pathogens

Question 5

What are the effector mechanisms of the innate immune response:

1. +3e.g
2. +3 e.g.

Answer 5

1. immediate defenses e.g. physical, chemical and microbiological barriers, complement and phagocytosis
2. Induced defenses e.f. cytokines &chemotaxis, interferon response (signal molecule about virus presence released by infected cells to warn over host cells)

Question 6

What effector mechanisms are involved in the adaptive immune response?

Answer 6

1. antibodies
2. cell-mediated immunity
3. memory

Question 7

What are the signs and symptoms of :

1. immediate defenses
2. induced defenses
3. adaptive immune response

Answer 7

1. none, natural homeostatic function
2. temporary disruption of homeostasis acute, localised inflammation
3. none, longstanding, effective protextion

Question 8

What is the result of malfunction of the immune response?

Answer 8

persistent or inappropriate inflammation, autoimmune disease e.g. Addison’s disease

Question 9

External body surfaces involved in protection: (3)

Answer 9

– Skin (keratin, cell-cell junctions)
– Nails (keratin)
– Ducts (fluid flow)

Question 10

How does skin protect?

Answer 10

– low pH inhibits microbial growth
– lactic acid from sweat glands lowers pH
– fatty acids from sebaceous glands lowers pH

Question 11

What damadge to the skin can result in penetration by bacteria?

Answer 11

Burns-moist surface, vascular damage

Question 12

why is it that sounds die of measles depsite the fact we have a very effective vaccine for measles?

Answer 12

The main reason is in hot climated countries such as Nigeria, the measles vaccine must be stored in a fridge. Furthermore, issues are access people in rural areas.

Question 13

What is another word for internal body surfaces?

Answer 13

mucosal surfaces

Question 14

Describe the properties of mucosal surfaces (5):

Answer 14

1. Large surface area
2. No keratin
3. Mucins (form mucus with water): coat microorganisms preventing attachment
4. ciliated epithelium (protection and ejection of large particles)
5. Flow of air and fluid

Question 15

What addition properties does the GI tract have to protect itself from infection:

Answer 15

Acid environment in stomach, bladder, kidney, bile

Digestive enzymes inhibit growth

Question 16

What addition properties does saliva add to the mouth to protect itself from infection:

Answer 16

• Lysozyme: digests bacterial cell walls

* Lactoferrin: removes iron required by bacteria

Question 17

Give 4 disorders caused by comprimised physical barriers:

Answer 17

• Abnormally thick mucus (e.g. in CF) leads to lung infections e.g. P. aeruginosa infection
• Corneal and ear infections upon water exposure
• Smoking damages ciliated epithelia in the airways
• Higher rate of sepsis after surgery in area of high flora e.g. colon

Question 18

How do commensal bacteria protect surfaces from pathogenic infection?

Answer 18

• Stimulate colonic epithelial cells giving a balanced state called physiological inflammation
• Compete with pathogens for nutrients, attachment sites and living space
• Fatty acids from propionibacteria are toxic to streptococci

Question 19

dysregulation of the interaction between colonic epithelial cells and commensal bacteria causes disease how?

Answer 19

1. dysregulaiton e.g. antibiotics kill commensal bacteria
2. pathogenic bacteria get a foot hold and produce toxins that cause mucosal injury
3. Neutrophils and red blood cells leak into gut between injured epithelial cells

Question 20

Give 3 examples of soluble mediators of the innate immune response:

Answer 20

1. enzymes
2. complement components
3. antimicrobial peptides

Question 21

Give examples of enzymes that are soluble mediators of the innate immune response:
2) What is their action?

Answer 21

1) lysozyme and phospholipase

2) digest cell walls and membranes respectively (in tears, saliva and phagocytes

Question 22

Give examples of enzymes that are soluble mediators of the innate immune response:
2) What is their action?

Answer 22

1) C3a: opsonisation
2) C3a and C5a: chemotaxis
3) C5b: membrane attack complex

Question 23

How many classes of AMP are there?

2) Give examples from 2 classes as well as what cell type in the body makes them:
3) What does AMP stand for?

Answer 23

1) 5
2) a)Charged peptides with cysteine e.g. alpha- defensins ,made by neutrophils and paneth cells, beta-defensins made by epithelial cells
b) peptide fragements e.g. lactoferin in saliva by serous epithelial cells
3) Antimicrobial peptides

Question 24

What action do AMPs have?

2) .. by virtue of what property?

Answer 24

1) disrupt cell membranes (Kill bacteria, fungi and enveloped viruses by perturbing their membranes )
2) by virtue of their amphipathic properties

Question 25

1) Where are cathelcidins found?
2) What do they do?
3) What is it a type of?

Answer 25

1) lysosomes of macrophages and polymorphonuclear leukocytes (PMNs), even epithelial cells
2) ptoent to microbes
3) AMP

Question 26

1) Where are histadins found?
2) What do they do?
3) What is it a type of?

Answer 26

1) serous fluid secreted by Ebner’s glands, salivary glands at the back of the tongue
2) play a role in wound-closure and offer proteciton form incoming microbes in the pharynx.
3)

Question 27

1) Where are lectins found?
2) What do they do?
3) What is it a type of?

Answer 27

1) leukocytes
2) a) they likely modulate inflammatory and autoreactive processes.
b) help mediate the first-line defense against invading microorganisms.
c) play a role in self-non-self discrimination
3) AMP

Question 28

What are paneth cells?

2) What do they make?
3) WHat do AMPs and enzymes kill?

Answer 28

1)Specialised epithelial cells of the small intestine
2) • Make a-defensins (also called cryptidins)
• Make lysozyme and phospholipase

3) enteric (gut) pathogens

Question 29

What are the 3 ways the compliment system can be activated? (IN ORDER OF HOW THEY REACT)

Answer 29

1) alternative
2) lectin
3) classical

Question 30

What is the alternative pathway?

Answer 30

pathogen surface creates local environment conductive to complement activation

Question 31

What is the lectin pathway?

Answer 31

mannose-binding lectin binds to pathogen surface

Question 32

What is the classical pathway?

Answer 32

C-reactive protein or antibody binds to specific antigen on pathogen surface

Question 33

What are the 3 main things the complement system does?

Answer 33

1. recruitment of inflammatory cells
2. opsonization of pathogens, facilitating uptake and killing by phagocytes
3. perforation of pathogen cell membranes

Question 34

How is perforation of pathogen cell membranes by complement system done?

Answer 34

formation of membrane attack complex with consequent disruption of bacterial outer membrane and bacterial cell death

Question 35

Describe what happens in opsonisation:

Answer 35

1) encapsulated bacteria cannot be engulfed by neutrophils
2) antibody bound to bacteria activates complement and bonding of C3b to bacteria
3) Engulfment of bacteria by neutrophils is mediated by Fc receptors and complement receptors
4) Granules fuse with pahgosomes rleasing toxic oxygen metabolites killing the bacteria