Immunology 6

Question 1

what are hypersensitivity reactions

Answer 1

abnormal/exaggerated reactions

Question 2

how many types of hypersensitivity reactions are there

Answer 2

4

Question 3

what type of antigens are present in TYPE 1 hypersensitivity reactions

Answer 3

airborne/soluble particles

Question 4

what’re the steps of the TYPE 1 hypersensitivity
+ what happens if re-exposure occurs

Answer 4

1. soluble antigens -> DC cells
2. DC=primes immune response + IgE released
3. IgE binds to mast cells (via Fc regions)
   = mast cell covered in outwards facing IgE
4. re-exposure = allergens bind to them + releases histamines

Question 5

what’s the usual reaction with TYPE I hypersensitivity reactions

Answer 5

wheal and flare

Question 6

what’re TYPE 2 hypersensitivity reactions

Answer 6

antigen binds to self structures
-become immunogenic

Question 7

what mediates TYPE 2 hypersensitivity reactions
+ what does it do

Answer 7

IgG
- activates complement
- induce phagocytosis + NK cells

Question 8

what type of antigens does TYPE 3 hypersensitivity reactions react to

Answer 8

soluble antigens

Question 9

what mediates TYPE 3 hypersensitivity reactions

Answer 9

Complexes formed by antigen-antibody complexes

Question 10

what’s the common reaction to a TYPE 3 hypersensitivity reacitons

Answer 10

rash/fever

Question 11

what type of reaction is a TYPE 4 hypersensitivity reaction

Answer 11

delayed hypersensitivity reaction

Question 12

what mediates TYPE 4 hypersensitivity reactions

Answer 12

effector t-cells
Th1 Th2 CTL

Question 13

what type of response is caused by autoimmune disease

Answer 13

adaptive response to self-antigens

Question 14

what’re the 3 factors that contribute to autoimmune diseases

Answer 14

1. genetic susceptibility
2. infection/environmental exposure
3. tolerance breakdown

Question 15

what’re the 2 types of autoimmune diseases

Answer 15

organ specific
systemic

Question 16

what animal does:
1. HIV-1
2. HIV-2
originate from

Answer 16

chimps
sooty mangabey

Question 17

what type of virus is HIV-1

Answer 17

retrovirus

Question 18

how does HIV-1 gain access to cells

Answer 18

via gp120 (surface protein)

Question 19

what’re the steps of infection by the HIV-1 virus

Answer 19

1. HIV enters via gp120 (binds to host CD4)
2. reverse transcriptase -> cDNA
3. viral cDNA integrates (integrase)
4. transcribed & translated
5. viral particles assemble + bud from host

Question 20

how does HIV-1 kill CD4 cells (3)

Answer 20

1. virus cytopathicity (direct killing)
2. apoctosis
3. cytotoxic t-cells (kills infected t-cells)

Question 21

when does AIDS occur

Answer 21

when CD4 level drops too low

Question 22

what can kill patients with AIDS

Answer 22

opportunistic bacteria

Question 23

how does HIV evade the immune system (3)

Answer 23

1. CD4 cells destroyed (normally used to fight disease)
2. antibodies can’t bind well to it
3. HIV rapidly mutates