Lecture 20

Question 1

what are hypersensitivity diseases

Answer 1

diseases caused by immune system

Question 2

how do hypersensitivity diseases work

Answer 2

when responses are not adequately controlled the immune system becomes the cause of the disease

Question 3

how many types of hypersensitivity diseases are there

Answer 3

4

Question 4

what is type 1

Answer 4

IgE mediated for allergic responses

Question 5

what are IgE responses needed for

Answer 5

responding to large complex molecules

Question 6

how does mast cell degranulation work

Answer 6

IgE binds to Fc receptor on the outside of the mast cell which activates the cell for degranulation. Granules are released off of the outside of the cell which causes a cross link between IgE and antigens on mast cells. this causes the release of mediators

Question 7

what are the mediators released during mast cell degranulation

Answer 7

chemoattractants, activators and spasmogens

Question 8

what are chemoattractants

Answer 8

tell other immune cells to get to sites

Question 9

what are activators

Answer 9

increase blood glow at the site

Question 10

what are spasmogens

Answer 10

compounds which have roles in muscle contractions and mucus secretions

Question 11

what are allergies

Answer 11

misdirected IgE responses

Question 12

what are 4 types of allergies

Answer 12

hay fever caused by dust pollen
insect stings caused by proteins in venom
food allergies caused by wheat protein, milk protein, peanuts
small molecules caused by penicillin, codeine

Question 13

what is the sensitisation phase

Answer 13

mast cells are coated with allergen specific IgE and remain armed for a period of time

Question 14

what does the sensitisation phase do

Answer 14

gets memory to allergen after first exposure

Question 15

what does IgE do during the sensitisation phase

Answer 15

sit on the receptor of the mast cell without the specific allergen bound

Question 16

what is the effector phase

Answer 16

allergen enters a second time while mast cells already armed triggering a hypersensitivity reaction

Question 17

what are the steps of the sensitisation and effector phase

Answer 17

1) first exposure to allergen
2) activation of Th2 cells and stimulation of IgE class switching to B cells
3) production of IgE specific to allergen
4) binding of IgE to Fc receptor on mast cells and gets hypersensitivity reaction from first exposure resulting in pre loaded mast cells towards specific allergen
5) repeat exposure to allergen
6) immediate activation of mast cells and release of mediators
7) immediately gets lots of symptoms occurring instantly

Question 18

what are the common sites of allergies

Answer 18

gut, skin, respiratory tract and multiple organs (anaphylaxis)

Question 19

what are treatments of allergies

Answer 19

avoidance, antihistamines, corticosteroids, epinephrine, desensitisation

Question 20

how are allergies tested for

Answer 20

blood test through the presence of IgE antibodies in blood and skin prick test which needles coated in diluted antigen

Question 21

what is the hygiene hypothesis

Answer 21

change in environment results in a change in lifestyle

Question 22

what is type 2

Answer 22

antibodies binding to antigens on the surface of cells and cause lysis

Question 23

what antibodies are present in type 2

Answer 23

IgM and IgG

Question 24

what do antibodies attack in type 2

Answer 24

mobile cells in bloodstream

Question 25

what is phagocytosis (hemolytic anemia)

Answer 25

IgG coated RBC are cleared from circulation via uptake of Fc receptor bearing macrophages and IgM coated RBC are fixed by complement and directly lysed

Question 26

what is goodpastures syndrome

Answer 26

antibodies against type 4 collagen in glomerular affects the kidney and aleveoli in the lungs

Question 27

what happens in goodpastures syndrome

Answer 27

antibodies trigger complement activation that damages epithelial cells

Question 28

what is type 3 mediated by

Answer 28

IgG

Question 29

what does type 3 do

Answer 29

antibodies bind antigens and form complexes which gets lodged into places it shouldnt be in and induces an inappropriate inflammatory response

Question 30

what is an example of type 3

Answer 30

rheumatoid arthritis and serum sickness

Question 31

what is type 4 mediated by

Answer 31

T cells

Question 32

how does type 4 mediated work

Answer 32

delayed hypersensitivity which results in trafficking

Question 33

what is an example of type 4

Answer 33

contact sensitivity caused by direct contact with certain antigens