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T cells/T cell receptors and Antigen Presenting Cells Flashcards

1
Q

What are the three cells of innate immunity?

A

Phgocytes, NK cells, Dendritic Cells

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2
Q

What are the two types of dendritic cells?

A

Antigen presenting (mDC) and Interferon-producing (pDC)

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3
Q

Cells of innate immunity are also cells of

A

Adaptive immunity

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4
Q

Have a variety of functions including phagocytosis, secretion of cytokines and antigen presentation

A

Dendritic Cells (DCs)

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5
Q

Collect proteins, some of which come from disease causing pathogens

A

Antigen Presenting Cells (APCs)

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6
Q

Break down the proteins into peptides (short protein fragments 8-15 amino acids)

A

APCs

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7
Q

APCs show these peptide fragments to

A

T cells

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8
Q

Initiate the adaptive immune response

A

APCs

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9
Q

Naïve T cells have not been exposed to

A

Antigen

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10
Q

Do little/nothing to directly clear infections

A

Naïve T cells

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11
Q

Produce effector molecules like cytokines (IL-4, IFN-γ)

A

Effector T cells

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12
Q

Long lived, antigen specific cells that respond very quickly if reexposed to same antigen; rapid production of effector molecules/functions

A

Memory T cells

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13
Q

Lymphocyte clones mature in generative lymphoid organs in the absence of

A

Antigens

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14
Q

Clones of mature lymphocytes specific for diverse antigens enter

A

Lymphoid tissues

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15
Q

Antigen-specific clones are then activted by

A

Antigens

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16
Q

The result is an antigen-specific

A

Immune response

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17
Q

Effector T cells and antibodies persist for weeks after exposure to antigen. This is called

A

Protective immunity

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18
Q

Innate immune system signaling (i.e. TLRs) activates

-Causing maturation

A

DCs

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19
Q

Must receive 2 signals to be fully activated

A

T cells

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20
Q

Costimulatory molecules are upregulated on

-following signals from the innate immune system

A

APCs

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21
Q

Binding of T-cell receptor (TCR) to the antigen-HLA complex on the dendritic cell (DC) delivers a signal (signal 1) that can induce

A

Activation and expansion of T cells

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22
Q

The costimulatory signal (signal 2) is given by binding of

A

CD28 to B7 molecules

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23
Q

Lack of costimulation inhibits

A

T cell responses

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24
Q

Lack of Costimulation Inhibits T cell Responses. This is one reason that

A

Tumors are hard to clear

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25
Malignant tumor cells express Tumor Restricted Antigen (TRA) but no costimulatory molecules. As a result, CD8 T cells specific for the TRA can not be
Activated
26
Upregulated on T cells after T cell is activated
CTLA-4
27
Also binds to B-7, but its function is to shut down the T cell response
CTLA-4
28
Cross-linking of CD28 delivers the co-stimulatory signal during activation of naive T cells and induces the expression of
CTLA-4 (CD152)
29
CTLA-4 is upregulated soon after T cell activation. It is essential for
Shutting down T cell responses
30
Mice without CTLA-4 die days after birth as a result of massive T cell infiltration of major
Organs
31
Therapeutic costimulatory blockades are used as a strategy to block the function of autoreactive T cells to prevent
Autoimmunity
32
To do this, we inject soluble CTLA-4 (CTLA-4-Ig) binds to B7 and prevents T cell from receiving signal 2 from
APC -as a result, T cell becomes anergic
33
We can enhance anti-tumor T cells by blocking the function of -patient will often experience autoimmunity as well
CTLA-4
34
What is the CTLA-4 blocker produced by Bristol-Myers Squibb?
Ipilimumab (Yervoy)
35
In the early signalling events in T cell activation, TCR complex and coreceptors cluster within membrane lipid rafts upon
Antigen recognition
36
Then, Lymphocyte specific protein tyrosine motif (LCK) phosphorylates tyrosines in
ITAM
37
Next, ZAP-70 binds to phosphotyrosines and phosphorylates adaptor proteins including
Linker for Activation of T cells (LAT)
38
Recognizes complex of viral peptide with MHC class I and kills the infected cell
Cytotoxic (CD8) T cells
39
What are the two typed of CD4 T cells?
TH1 and Helper T cells
40
Recognizes complexes of bacterial peptides with MHC class II and activated macrophages
TH1
41
Recognizes complexes of antigenic peptide with MHC class II and activates B cells
Helper T cells
42
Functions to stimulate IgG production
TH1 cells
43
Stimulates the production of IgE
TH2 cells
44
Functions in classical macrophage activation and enhanced microbial killing
TH1
45
two of the main functions of TH2 are
Antibody production and mast cell degranulation
46
Also functions in intestinal mucus secretion and peristalsis and eosinophil activation
TH2 cells
47
TH2 cells can also function in as an alternative for macrophage activation which results in
Enhanced fibrosis/tissue repair
48
Functions in inflammation and to generate anti-microbial peptides. The also increase barrier function
TH17 cells
49
Inhibit T cell activation and T cell effector functions
Regulatory (Tregs) T cells
50
What are the 4 mechanisms of Treg function?
1. ) DC targeting 2. ) Inhibitory cytokines 3. ) Cytolysis 4. ) Metabolic disruption
51
Peptides from pathogens are presented to T cells in the context of
MHC
52
What happens if the pathogen changes such that its peptides cannot be presented by MHC?
No immune response will occur
53
Simian Immunodeficiency Virus (SIV) escapes CD8 T cells by mutating amino acids necessary for binding to
MHC class I
54
Cytotoxic T-lymphocyte (CTL) responses to human immunodeficiency virus arise early after
Infection
55
Human immunodeficiency virus may evade the CTL response by accumulating amino-acid replacements within
CTL epitopes
56
TCRs must bind to your MHC molecules, but not bind too strong (high avidity) such that the T cell is activated and causes
Autoimmunity
57
Selects the useful T cells, eliminates the dangerous T cells, and ignores the rest
T cell development
58
Picks out the T cells with useful TCRs
Positive selection
59
What percentage of thymocytes fail positive selection and die?
95%
60
Eliminates the T cells with dangerous TCRs
Negative selection
61
What percentage of positively selected thymocytes are subsequently killed by negative selection
70%
62
T cell recognition of self peptide-MHC is necessary for both
Positive and Negative Selection
63
Expression of MHC in the thymus is required for
Positive selection
64
T cell subsets develop in the
Thymus
65
What are the 4 T cell subsets that develop in the thymus?
1. ) CD4+ T cells 2. ) CD8+ T cells 3. ) Treg T cells 4. ) NKT cells
66
Making sure your immune system does not attack your own body
Immunological Tolerance
67
What are the two types of immunological tolerance?
Central tolerance and peripheral tolerance
68
Occurs in the thymus (T cells) and bone marrow (B cells)
Central Tolerance
69
The affinity of the TCR on developing thymocytes determines if the cell is
Positively or negatively selected
70
Thymic function decreases with
Age
71
In the aged thymus, the perivascular space (P) is increased in size and the thymopoietic cortex (C) and medulla (M) are significantly
Constricted
72
The TCR repertoire of the naive and memory CD4+ T cell compartments changes with
Age
73
A cure for leukemia and other cancers, and a fantastic tool to study the immune system *The bone marrow chimeric mouse
Bone marrow transplant
74
Killed by chemotherapy and radiation
Hematopoetic Cells
75
Not killed by chemotherapy and radiation
Epithelial/stromal cells
76
After a bone marrow transplant, immune cells will have genotype of the donor, while the epithelial/stromal cells will have the genotype of the
Host
77
Cell surface marker on all hematopoietic cells
CD45
78
What are the 5 steps of a bone marrow transplant to cure cancer?
1. ) Collection 2. ) Processing 3. ) Cryopreservation 4. ) Chemotherapy 5. ) Reinfusion
79
Death after a bone marrow transplant is often caused by infection because T cells do not
Reconstitute
80
Multi-potent cells are directed into the
T cell lineage
81
RAG1/2 (Recombination Activating Genes 1 /2 are expressed and mediate
V(D)J recombination of the TCR loci
82
Thymocytes undergo positive selection and then undergo
Negative selection
83
Then, multiple lineages are defined such as
CD4, CD8, Treg, etc
84
The selected thymocytes have TCRs that are
MHC restricted
85
Experimental results showed that T cells cannot respond to cells from different strains of mice infected with the same
Same virus

Immunity (33 decks)

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