10. Cell mediated acquired immune responses Flashcards
1
Q
where are intracellular vesicular pathogens?
A
phagocytosed in membrane-bound compartments
2
Q
where are intracellular cytoplasmic pathogens?
A
cytosol
3
Q
what are intracellular vesicular pathogens recognised by?
A
helper T cells
4
Q
what are intracellular cytoplasmic pathogens recognised by?
A
Cytotoxic T cells
5
Q
what are extracellular pathogens recognised by?
A
B cells
6
Q
3 types of APC
A
- dendritic
- macrophage
- b cell
7
Q
where are APcs?
A
secondary LT
8
Q
steps of dendritic cell maturation
A
- pathogen phagocytosis
- dendritic cell matures in epidermis - express MHC, cytokines and TLR
- DC migration to lymph node
- T cell enters lymph node
- T cell receptor recognises Ag on DC (APC)
- T cell migration to site of infection
9
Q
which cells detect MHC I?
A
CD8
10
Q
which cells detect MHC II?
A
CD4
11
Q
what is the TCR complex made of?
A
variable alpha and beta fragment
12
Q
what is the MHC complex made of?
A
alpha 1,2 and 3
B2m fragments
13
Q
what joins the TCR and MHC complexes together?
A
peptides
14
Q
what type of pathogens do CD8 cells respond to?
A
intracellular cytoplasmic
15
Q
what type of pathogens do CD4 cells respond to?
A
intracellular vesicular
16
Q
3 connections between APC and CD8 Tc cell for activation?
A
- MHC I and CD8+
- B7 and CD28
- IL-12 and IL-2 released
17
Q
steps in CD8 proliferation and differentiation?
A
- CD8 autocrine release of IL-2
- IL-2 binds to high affinity IL-2 receptors on T cell
- stimulates proliferation and differentiation
- differentiation into memory and effector cells
18
Q
what occurs after CD8 proliferation and differentiation?
A
- Tc leave secondary LT and enter blood
2. Tc recognise MHC I/Ag complex on infected cells
19
Q
2 ways CD8+ cells kill cels
A
- Fas
2. Perforin and granzyme
20
Q
describe apoptosis by CD8 by fas
A
- fas ligand (Tc) binds to Fas on target cell
2. triggers extrinsic apoptopic pathway
21
Q
describe perforin/granzyme steps in CD8 apoptosis pathway
A
- TCR attach to MHC I (target cell)
- Cell adhesion - LFA-1 (tc) binds to ICAM-1 (target cell)
- Tc releases granzyme and perforin into immune synapse
- perforin = induces granzyme uptake by cell and its cytoplasmic release
- granzyme B = cleaves pro-caspase - creates caspase 3
- apoptosis
22
Q
4 diseases which causes resistance against Tc cell
A
- herpes simplex virus
- cytomegalovirus
- epstein-Barr virus
- Pox virus
23
Q
Herpes simplex virus resistance against T cell
A
inhibition of Ag presentation
24
Q
Cytomegalovirus resistance against T cell
A
inhibition of Ag presentation - removes MHC I
25
Epstein-Barr resistance against T cell
inhibition of Ag presentation - produces IL-10 - inhibits macrophage + DC activation
26
pox virus resistance against T cell
inhibition of effector cell activation - blocking cytokines
27
effector functions of Th
secrete cytokines which cause the stimulation of:
| Tc cells, neutrophils, B cells, macrophages
28
3 examples of cytokines
- IL-17
- tumour necrosis factor
- chemokines
29
what type of chemicals are cytokines
glycoproteins
30
function of IL-17
secreted by Th cells to stimulate bone marrow to increase neutrophil proliferation by GM-CSF
31
what is GM-CSF
granulocyte -macrophage colony-stimulating factor
32
5 different type of Th cell?
Th1, Th2, Th17, TFH, Treg
33
which cell are all of the Th cells produced from?
Th0
34
which Th cell defends against intracellular bacteria?
Th1
35
what does Th2 provide defence against?
Heliminths
36
which Th cell defends against extracellular bacteria and fungi ?
Th17
37
what does ThFH defend against
extracellular pathogens
38
role of Treg
regulatory role of suppressing the immune system
39
what cytokines do Th1 produce?
IFN-gamma
40
what 3 cytokines do Th2 produce?
IL-4, IL-5 and IL-13
41
what 3 cytokines do Th17 produce?
IL-17a, IL-17F and IL-22
42
describe steps in TH1 production
1. intracellular bacteria enters body
2. APC interacts with TH0 cell
- B7 and CD28
- MHCII and CD4
3. APC releases IL-12
4. NK releases IFN-y
5. differentiation of TH0 into TH1
43
3 effector functions of TH1
1. macrophage activation
2. B cell production of IgG
3. Tc maturation
44
describe effector function of TH1 in terms of macrophage activation in steps
1. TH1 releases IFN-y
2. macrophage interacts with TH1 cell
- IFN-y and CD40L
3. macrophage activation
4. enhanced phagocytosis
45
describe effector function of TH1 in terms of B cell activation in steps
1. TH1 releases IFN-y
2. activates B cell
3. B cell produces IgG
4. IgG used as adaptor molecule for complement and opsonisation
46
describe effector function of TH1 in terms of Tc cell activation in steps
1. TH1 releases IFN-y
2. causes APC to release cytokines which activate Tc maturation
3. directly activates Tc maturation
47
describe steps in TH2 production
1. helminth enters body
2. interaction between APC and T cell (B7-CD28, MHC II, CD4)
3. secretion of IL-4 from mast cells and eosinophil and autocrine Th
4. differentiation into Th2
48
3 effector functions of Th2
1. B cell production of IgG4 and IgE
2. macrophage activation
3. eosinophil activation
49
describe effector function of TH2 in terms of B cell activation in steps
1. TH2 release Il-4
2. stimulates B cell to produce IgG4 and IgE
3. IgE causes mast cell degranulation against helminths
50
describe effector function of TH2 in terms of macrophage activation in steps
1. Th2 release IL-4 and IL-13
2. stimulate macrophage
3. enhanced phagocytosis
51
describe effector function of TH2 in terms of eosinophil activation in steps
1. Th2 releases IL-5
| 2. activates eosinophils
52
describe steps in TH17 production
1. extracellular bacteria/fungi enter body
2. interaction between APC and CD4 cell
3. APC releases IL-6, IL-23, TGF-beta
4. autocrine secretion of IL-21
5. differentiation into TH17
53
2 effector functions of Th17
1. leukocyte stimulation of neutrophils
| 2. antimicrobial peptides from tissue cells
54
describe effector function of TH17 in terms of neutrophil activation in steps
1. TH17 secretes IL-17
2. causes leukocytes to stimulate neutrophil production
3. also causes BM to release GM-CSF which stimulates neutrophil production
4. neutrophils cause inflammation
55
which cytokine is secreted from Th-17 to increase antimicrobial peptides ?
IL-22
56
2 effector functions of TFH
1. B cell proliferation
| 2. B cell differentiation into plasma cells
57
how does TFh cause B cell proliferation
Tfh recognise Ag and MHC II
58
which cytokines does Tfh release to cause B cell differentiation into plasma cells
IL-21
59
function of Treg
down regulation of cytokines - losing cell function
60
what cytokine is released from Treg, what does it do?
TGF-beta
| inhibits function of TH2 and TH1
61
which other 2 cytokines, apart from TGF-beta, are involved in Treg? what do they do?
1. IL-4 (Th2)
inhibits function of TH1 and TH17
2. IFN-y (TH1)
inhibits function of TH2 and TH17
62
which cell does HIV deplete?
CD4+ helper T cells
63
describe HIV pathophysiology in steps
1. HIV attacks
2. immune response (Anti-HIV Abs, HIV-specific Tc cells)
3. clinical latency - virus trapped in LT by follicular DC- low levels of viral production
4. increase in viral production
5. virus kills LT and CD4 cells
64
3 consequences of HIV infection
1. AIDS
2. Infection /cancer
3, death
