EXAM 3 T Cell-Mediated Immunity Flashcards
(77 cards)
1
Q
Describe CD8 T cells
A
- kills infected or diseased cells
- direct effector T cell arm
- targeted
- repeated activity until inhibited
2
Q
describe CD4 T cells
A
- enhance innate and adaptive immunity
- regulatory T cell arm
- targeted
- direct and indirect effector functions; can kill
3
Q
describe the basic process of T cell activation and differentiation
A
for both CD8 and CD4 T cells:
- antigen presenting cell interacts with naive T cell (antigen recognition)
- T cells are activated by IL-2 and IL-2R (same for CD8 and CD4)
- clonal expansion
- differentiation
- effector cell and memory cell
- CD4 - activation of macrophages, B cells, other cells
- CD8 - killing of infected target cells; macrophage activation
4
Q
___ initiates T cell immunity
A
antigen presentation
5
Q
___ are the most common T cell activator
A
dendritic cells
6
Q
dendritic cells must be ___, and presentation occurs in ___
A
- activated
- secondary lymphoid organs
7
Q
tissue dendritic cells take up antigen by what 2 mechanisms?
A
macropinocytosis and phagocytosis
8
Q
MHC expression is ___ on immature DCs and ___ on DCs in lymphoid tissue
A
- low
- high
9
Q
describe the location of DCs in the body
A
ubiquitous throughout the body
10
Q
what are the 3 antigen presenting cells?
A
dendritic cells, macrophages, and B cells
11
Q
which antigen presenting cell is primarily responsible for presenting antigen to T cells?
A
dendritic cells
most common and most prevalent T cell activator
12
Q
dendritic cells mature though ___
A
antigen activation
13
Q
describe the process of DC maturation via antigen activation
A
- immature DCs in peripheral tissues encounter pathogens and are activated by PAMPs
- TLR signaling induces CCR7 and enhances processing of pathogen-derived antigens
- CCR7 directs migration into lymphoid tissues and augments expression of co-stimulatory molecules and MHC molecules
- mature dendritic cell in T-cell zone primes naive T cells
14
Q
DCs are targeted to lymph nodes by ___ binding ___ and ___
A
- CCR7
- CCL19 and CCL21
15
Q
dendritic cells take up bacterial ___ in the skin and then move to enter a draining lymphatic vessel. DCs bearing ___ enter the draining lymph node, where they settle in the ___ areas
A
- antigen
- antigen
- T-cell
16
Q
where do the different antigen presenting cells distribute in lymph nodes?
A
- DCs - T cell areas
- macrophages - all areas
- B cells - B cell areas
17
Q
DCs present antigen by ___ and ___
A
MHC I and II
18
Q
___ is critical for CD8 T cell activation
A
cross-presentation
19
Q
what 2 ways do DCs present antigen to CD4 T cells?
A
- receptor-mediated endocytosis of bacteria
- macropinocytosis of bacteria or viruses
20
Q
what 3 ways do DCs present antigen to CD8 T cells?
A
- viral infection
- cross-presentation of exogenous viral antigens
- transfer of viral antigens from infected DC to resident DC
21
Q
naive T cells can enter a draining lymph node by which two routes?
A
- in the blood
- in the afferent lymph coming from an upstream lymph node
22
Q
___ monitor antigens presented by DCs
A
naive T cells
23
Q
naive T cell population rotates/circulates through ___, resulting in ___
A
- lymph nodes
- systemic antigen exposure (aka systemic ability to target infection)
24
Q
T cells and DCs form immune ___
A
synapses
the strength of the synapse dictates whether or not the T cell will be activated
25
T cell activation requires which 3 signals?
* activation
* survival
* differentiation
* \*process is the same for both CD4 and CD8 T cells
26
antigen presenting cells deliver 3 kinds of signals to naive T cells to activate them. describe.
1. T Cell Receptor
* Peptide recognition
* MHC I or II
* CD8 or CD4
2. Co-stimulatory Molecules
* Survival signal
* B7 family (APC)
* CD28 family (T cell)
* B7-CD28 required for T cell activation
3. Cytokines
* Paracrine and autocrine
* Propagation (IL-2)
* Differentiation
* IL-2: CD8, All TH
* IL-4: TH2
* IL-6: TFH
* IL-12: TH1
* TGF-β + IL-16 + IL-23: TH17
* TGFβ: Treg
27
naive T cell TCR activation in the absence of co-stimulation (from ___ and \_\_\_) leads to \_\_\_
* B7 and CD28
* anergy
28
describe co-stimulation of T cells and antigen presenting cells, which is required for T cell activation
29
activation induces T cell changes in what 5 ways?
* differentiation
* clonal expansion
* changes in surface protein expression
* migration to target tissues
* effector functions
30
in what ways does activation induce T cell differentiation?
* CD8 T cells
* effector cells, memory cells
* CD4 T cells
* Th1, Th2, Th17, Tfh, Treg
* effector cells, memory cells
31
activated can induces T cells to migrate to which two target tissues?
* lymph nodes
* sites of infection or damage
32
how does activation induce changes in T cell molecule expression?
* upregulates expression of adhesion, signaling, and protease molecules
33
which IL drives clonal expansion?
IL-2
34
IL-2 drives clonal expansion in ___ T cell lineages, and involes what kind of signaling?
* all
* autocrine
35
how does IL-2 drive clonal expansion?
T cells produce their own IL-2, stimulation to more sensitive IL-2 receptor, driving proliferation (clonal expansion)
36
\_\_\_ inhibits continued T cell activation and proliferation
describe how this works
CTLA-4
* T cells don't die after effector functions are performed
* CTLA-4 is expressed on activated T cells
* binding an antigen presenting cell after activation leads to T cell inhibition
* B7 binds CTLA-4 20-fold stronger than CD28
37
what is CTLA-4?
cytotoxic T lymphocyte-associated protein 4
38
do CD8 T cells dies once their effector function is complete?
no; they kill repeatedly
39
CD8 T cells only kill cells expressing targeted peptide via \_\_\_
MHC I
40
how many ways can naive CD8 T cells be activated?
2
41
describe the two ways that naive CD8 T cells can be activated
* DCs infected with some types of virus can activate a naive virus-specific T cell on their own
* DCs infected with some viruses need help to activate a naive virus-specific CD8 T cell
42
CD8 T cells kill through ___ and \_\_\_
perforin and granzymes
43
how do CD8 T cells kill through perforin and granzymes?
44
what are the 3 proteins in granules of cytotoxic T cells?
perforin, granzymes, and granulysin
45
what is the action of perforin on target cells?
aids in delivering contents of granules into the cytoplasm of target cell
46
what is the action of granzymes on target cells?
serine proteases, which activate apoptosis once in the cytoplasm of the target cell
47
what is the action of granulysin on target cells?
has antimicrobial actions and can induce apoptosis
48
DCs have ___ that dictate what ILs they express when they are presenting pathogen
PPRs
49
\_\_\_ drives a cellular mediated response to a pathogen
Th1
50
\_\_\_ drives a humoral response to pathogen
Th2
51
CD4 Th1 and Th2 differentiation involves what 3 things?
* cytokine induction
* transcription factor
* effector cytokines
52
\_\_\_ induce CD4 T cell subtype differentiation
cytokines
53
what is Th0?
naive CD4 T cell
54
which cytokines lead to the production of Th1 cells, and what is the function of Th1 cells?
* IL-12 and IFN-gamma
* activate macrophages
55
which cytokines lead to the production of Th17 cells, and what is the function of Th17 cells?
* IL-16, TGF-beta, and IL-23
* enhance neutrophil response
56
which cytokines lead to the production of Th2 cells, and what is the function of Th2 cells?
* IL-4
* activate cellular and antibody response to parasites
57
which cytokines lead to the production of Tfh cells, and what is the function of Tfh cells?
* IL-6 and IL-21
* activate B cells, maturation of antibody response
58
which cytokines lead to the production of Treg cells, and what is the function of Treg cells?
* TGF-beta
* suppress other effector T cells
59
how do Th1 cells activate macrophages?
60
describe activated macrophages
* express co-signaling ligands
* kill intracellular pathogens
* release cytokines and antimicrobial effectors
* present antigen
61
Th1 cells form ___ when pathogens cannot be cleared
granulomas
62
what is a granuloma that Th1 cells form when pathogens cannot be cleared?
* a compact aggregate of leukocytes that sequester a pathogen
* occurs during chronic inflammation
* infectious and non-infectious agents
* several types
* pyogenic granulomas are not true granulomas
63
Th1 cytokines enhance the ___ response
induced innate
64
what are the cytokines that activated Th1 cells express?
* IFN-gamma and CD40 ligand
* Fas ligand or LT-beta
* IL-2
* IL-3 + GM-CSF
* TNF-alpha and LT-alpha
* CXCL2
65
when activated Th1 cells express IFN-gamma and CD40 ligand, what happens?
activates macrophage to destroy engulfed bacteria
66
when activated Th1 cells express Fas ligand or LT-beta, what happens?
kill chronically infected cells, releasing bacteria to be destroyed by fresh macrophages
67
when activated Th1 cells express IL-2, what happens?
induces T cell proliferation, increasing numbers of effector cells
68
when activated Th1 cells express IL-3 + GM-CSF, what happens?
induces macrophage differentiation in the bone marrow
69
when activated Th1 cells express TNF-alpha + LT-alpha, what happens?
activates endothelium to induce macrophage binding and exit from blood vessel at site of infection
70
when activated Th1 cells express CXCL2, what happens?
causes macrophages to accumulate at site of infection
71
\_\_\_ cells activate B cells and induce class switching
Tfh
72
how do Tfh cells activate B cells?
73
how do Treg cells suppress other T cells?
74
\_\_\_ and ___ cells regulate mucosal inflammation
Th17 and Treg
75
Th17 and Treg cells are enriched in the \_\_\_
gut
76
how do Th17 and Treg cells regulate mucosal inflammation?
* Treg cells inhibit mucosal inflammation
* Th17 cells:
* neutrophil recruitment
* antimicrobial peptide production
* tissue repair
77
persistent Th17 can be negatively involved in which autoimmune disorders?
* rheumatoid arthritis
* multiple sclerosis
* psoriasis
* inflammatory bowel disease
