Comparative Immunology > Lecture 2

Front 1

Describe the physiology of epithelial cells.

Back 1

- tightly joined together by adhesion molecules & tight junction proteins

- replaced by underlaying stem cells

- POLARIZED MORPHOLOGY (apical side exposed to commensal microbes/environment and basolateral side protected from exposure)

Front 2

Where are PRRs found on epithelial cells?

Back 2

concentrated on basolateral side

- commensal microbes tolerated on apical side

- PRRs alert underlaying immune system of microbial invaders/tissue damage

Front 3

What are the functions of the skin?

Back 3

1. nutrient synthesis

2. thermoregulation

3. osmoregulation

4. protective barrier against stressors
(UV radiation, chemical exposure, microbes)

Front 4

What are the differences between the skin of cartilaginous fish vs. bony fish?

Back 4

- cartilaginous fish have PLACOID SCALES that rise out of epidermis to protect skin

- bony fish covered with MULTILAYERED EPIDERMIS that is coated in mucus (contains antimicrobial proteins/peptides)

Front 5

What is the function of Goblet cells?

Back 5

- produce mucus

Front 6

What is the function of mucus?

Back 6

- protect viable epidermis from surrounding environment

Front 7

What are the functions of melanophores?

Back 7

1. provide skin pigmentation

2. help to sequester reactive oxygen species that are generated during oxidative stress

Front 8

Where are neural sensory cells located on a fish?

Back 8

- along the lateral line

Front 9

What is the stratum corneum function?

Back 9

- non-viable layer of cells covered by epidermis

- constantly replaced by epithelial cells called keratinocytes (differentiate from underlaying pluripotent stem cells)

- only found in birds and mammals

Front 10

What is the function of the stratum corneum?

Back 10

- protects underlaying viable epidermis from abrasion, water loss, UV radiation, toxic chemicals & microbial invasion

Front 11

What are two differences found in the skin of birds?

Back 11

- avian skin lacks sweat glands

- uropygial gland replaces the sebaceous glands of mammals (produces lipids to condition feathers and repel water)

Front 12

How are hair and feathers produced?

Back 12

from keratin produced by keratinocytes

Front 13

What are the functions of hair/feathers?

Back 13

1. thermoregulation

2. protective barrier

Front 14

Besides producing hair/feathers, keratinocytes also play an important role in the immune response. Describe.

Back 14

keratinocytes protect against invasion and maintain tolerance to commensal microflora by communicating with the SALT
(skin-associated-lymphoid-tissue)

Front 15

What does hair thickness influence?

Back 15

- skin conditioning

- attachment of parasites

(potential disease vectors)

- potential damage caused by skin abrasion

Front 16

What 4 mammalian epidermis factors are highly variable across species?

Back 16

1. hair thickness

2. stratum corneum thickness

3. amount of melanocyte pigmentation

4. sebaceous gland secretions

Front 17

What does dark skin pigmentation allow for?

(thicker stratum corneum, higher lipid content, and replaced more rapidly)

Back 17

1. retain water effectively

2. more resistant to chemical and microbial exposure

3. nutritionally adaptive feature

Front 18

What diseases are LIGHT skin humans susceptible to?

Back 18

- spina bifida

- caused by UV-induced folic acid depletion during pregnancy

Front 19

What diseases are DARK skin humans susceptible to?

Back 19

- Rickets disease

- immunodeficiency

- caused by insufficient vitamin D production during pregnancy and early life

Front 20

What is specific to cattle epidermis?

Back 20

- very thick stratum corneum

Front 21

What is specific to sheep epidermis?

Back 21

- secrete unique moisture barrier made of lanolin (long chain waxy esters rather than oils) from sebaceous glands

Front 22

How are sweat glands distributed on primates?

Back 22

distributed all over the body

(allows for efficient thermoregulation)

Front 23

What determines the number of FUNCTIONAL sweat glands on the mammalian body?

Back 23

environmental temperatures experienced during early life epigenetically affect # of sweat glands that are functional

Front 24

What two compounds does sweat contain? What are their functions?

Back 24

1. dermicidin

2. lactoferrin

- antimicrobial peptides that help control microbial invaders and commensal microbes

Front 25

Where are the sweat glands of hooved animals found?

Back 25

under the axilla (armpits)

Front 26

Where are the sweat glands of pigs, dogs & cats found?

Back 26

concentrated on footpads and snout

Front 27

What is a hapten?

Back 27

small molecular weight reactive chemicals

<1000 Da

- can be found in cosmetics, jewellery, cleaning agents

Front 28

What is allergic contact dermatitis?

Back 28

repeated exposure to happens causes a cell-mediated hypersensitivity reaction that develops into a disease called allergic contact dermatitis

Front 29

What is mucus? What is it made of?

Back 29

- a gel gradient

- composed of:

a) mucin proteins

b) lipids

Front 30

What are the functions of mucus? (7)

Back 30

1. physical barrier preventing attachment

2. lubricates to reduce abrasion

3. traps and removes microbes, antigens, chemicals (facilitated by TURBULENT AIRFLOW in trachea and bronchi)

4. maintains hydration

5. outer loose layer acts as adhesive surface

6. inner dense layer provides a matrix to concentrate antimicrobial proteins

7. facilitates removal of motile immune cells that have engulfed foreign particles

Front 31

What is the function of epithelial cells in nasal and oral cavities, trachea and bronchi?

Back 31

- protect against pathogen invasion

- facilitate tolerance to commensal microflora

- communicate with NALT & BALT

Front 32

What are the functions of Goblet cells in nasal and oral cavities? (2)

Back 32

- produce mucus

- produce surfactant proteins

Front 33

What is the function of Clara cells?

Back 33

secrete antimicrobial proteins and peptides

Front 34

What is the function of M-cells?

Back 34

sample antigens from mucus and pass them along underlaying tissue macrophages and DC for antigen-presentation

Front 35

What are pneumocytes?

Back 35

epithelial cells that make up the alveolar sacs

Front 36

What is the function of Type 2 pneumocytes?

Back 36

Type 2

- replace Type 1

- produce surfactant proteins that reduce surface tension preventing lung collapse

- antimicrobial and immunomodulatory properties

Front 37

How is mucus removed?

Back 37

beating of ciliated epithelial cells & coughing

Front 38

What is the Hygiene Hypothesis?

Back 38

lack of exposure to certain microbes during early life development can affect immune development and increase risk of atopic diseases

Front 39

What are atopic diseases? Examples?

Back 39

- caused by antibody-mediated hypersensitivity reactions

- ex. asthma, food allergy, atopic dermatitis

Front 40

What makes up the small intestine epithelium?

Back 40

finger-like villi and gland-like crypts

Front 41

What is the function of SI crypts?

Back 41

contain pluripotent stem cells that proliferate and differentiate into other epithelial cell types

(ex. absorptive enterocytes, Goblet cells, enteroendocrine cells, M-cells, Panth cells)

Front 42

What is the function of Panth cells in the SI?

Back 42

secrete antimicrobial peptides

Front 43

What are the major differences between the small and large intestine epithelium?

Back 43

large intestine is

i) NOT lined with villi

ii) Panth cells are NOT found

iii) cells communicate with GALT