T cell activation

Question 1

activation is not initiated until the second signal is received by a co-stimulator ___________________________ between the APC and naïve T cell

Answer 1

receptor-ligand binding pair

Question 2

what is the purpose of plasmacytoid dendritic cell?

Answer 2

involved in the early stages of innate immune response secreting anti-viral cytokines IFNa and IFNb. They are key players against viral infections

Question 3

what is the purpose of myeloid dendritic cells?

Answer 3

involved in T cell activation. These dendritic cells are found throughout the tissues
of the body in sites of antigen exposure (i.e. skin)

Question 4

what is the dendritic cell in the skin?

Answer 4

langerhans cell

Question 5

what are immature dendritic cells?

Answer 5

dendritic cells that have not been activated tend to express high levels of antigen receptors for pathogens (i.e. Toll-like receptors and phagocytic receptors), but low levels of MHC on their cell surface

Question 6

what happens if a mature dendritic cell already resides in secondary lymphoid tissue?

Answer 6

it would initiate Ag presentation to T cells and B cells accompanied by the secretion of cytokines (i.e. IL-12

Question 7

what would happen if the mature dendritic cell resided in peripheral tissues like Langerhans cell?

Answer 7

in addition to the upregulation in MHC class I and MHC class II molecules, the dendritic cell would upregulate adhesion molecules and chemokine receptors to aid in its migration into the lymphatics and ultimately to the draining lymph nodes to present processed Ag to the circulating naïve T cells or memory T cells, if the host had encountered the antigen previously

Question 8

how does the dendritic cell become mature?

Answer 8

Upon recognition and internalization of foreign antigens (i.e. pathogens), the dendritic cell is
activated and changes it cell surface protein expression molecules toward an increase in MHC molecules bound with linear peptide Ag

Question 9

what do activated APCs express?

Answer 9

a multitude of MHC molecules with different linear Ag peptides with the potential to activate many different T cells

Question 10

why does MHC and TCR have such a low affinity binding event?

Answer 10

association between the MHC and TCR is based on such a small peptide and only components (i.e. amino acid sequences) of that peptide.

Question 11

what stabilizes the MHC-TCR binding and also lowers the threshold of T cell activation?

Answer 11

additional binding of the co-receptor (i.e. CD4) to the invariant portion of the MHC

Question 12

what is B7-CD28 binding required for?

Answer 12

second signal and T cell activation

Question 13

what is upregulated upon activation of T cells?

Answer 13

CD152

Question 14

what deactivates the T cell with expression of CD152?

Answer 14

if bound by CD80 or 86

Question 15

what is upregulated when the T cell becomes activated and upregulating the expression of the CD80 or CD86 molecules and also has important role when T cells interact with B cells in antibody synthesis?

Answer 15

CD154

Question 16

list 3 adhesion molecules

Answer 16

CD54 (ICAM-1)-CD11a/CD18 (LFA-1), CD58 (LFA-3)- CD2, and LFA-1-CD50 (ICAM3)

Question 17

define immunologic synapse?

Answer 17

collective association of the MHC-TCR, co-receptors and adhesion molecules between the
APC and T cell

Question 18

how do we creen these cell surface
molecules to evaluate the different stages of cell activation as well as help determine if there is a defect cell surface molecule when we suspect some abnormal immune response?

Answer 18

flow cytometry

Question 19

what does linker for activation of T cells (LAT) serve as?

Answer 19

an adapter protein to bind more proteins such as SLP76. This protein when bound promotes the reorganization of cellular actin as well as binding to phospholipase Cγ1 (PLCγ1)

Question 19

what does linker for activation of T cells (LAT) serve as?

Answer 19

an adapter protein to bind more proteins such as SLP76. This protein when bound promotes the reorganization of cellular actin as well as binding to phospholipase Cγ1 (PLCγ1)

Question 20

Upon binding of the MHC-peptide TCR, _________ kinases Fyn and Lck (members of Src family) are activated via dephosphorylation by membrane-bound protein CD45 and are drawn to the ITAMS on the cytoplasmic domains of the CD3 and ζ chains.

Answer 20

tyrosine

Question 21

______ is a key mediator of 3 distinct cell signaling pathways all of which result in the activation of transcription factors

Answer 21

PLCγ1

Question 22

The impact of the second signal B7-CD28 at the intracellular level promotes lipid rafts to
transport additional kinases and other molecules to the TCR site to enhance signaling. In addition, binding of B7-CD28 attracts the enzyme phosphatidylinositol-3 (PI3). It is believed that these combined events serve to promote ____ synthesis by increasing the rate of ____ gene transcription

Answer 22

IL-2

Question 23

how has the calcineurin pathway been used as a therapeutic target?

Answer 23

to downregulate T cell activation following tissue/organ transplantation

Question 24

Upon activation of the T cell (naïve or mature), what is the goal of the adaptive immune system?

Answer 24

proliferate

Question 25

This first and second signal response activates a number of intracellular signaling pathways that results in the activation of what 3 transcription factors?

Answer 25

NFAT, NFκ-B and AP-1

Question 26

transcription factors activated transcribe select gene segments in activated T cell to yield a host of proteins to promote what?

Answer 26

cell proliferation

Question 27

In resting T cells, IL-2R exists as a ____ affinity 2-chain surface protein and upon activation of the T cell it changes to the ____ affinity 3-chain surface protein

Answer 27

low
high

Question 28

what kind of signal is classified as a molecule produced by a cell that stimulates or activates the same cell?

Answer 28

autocrine

Question 29

describe paracrine signal?

Answer 29

A molecule produced by a cell that locally affects other cells

Question 30

describe endocrine signal

Answer 30

A molecule that is produce by a cell and affects cells elsewhere in the body

Question 31

what two kind of signals does IL-2 function as?

Answer 31

autocrine and paracrine

Question 32

what does the cluster of homing molecules
that are upregulates would appear to determine ?

Answer 32

which tissue a particular T cell will migrate

Question 33

activated T cells upregulate the expression of
the ______ as a “shutdown” control switch

Answer 33

CD152 (CTLA-4)

Question 34

what is the program cell death CD279 (PD-1) protein role?

Answer 34

inducing “exhausted T cells” to die, suppressing activated T cells (i.e autoreactive T cells) and rescuing regulatory T cells.

Question 35

______ is expressed on many normal cells as well as most cancer cells

Answer 35

PD-L1

Question 36

______ is more restricted to dendritic cells and some tumor cells

Answer 36

PD-L2

Question 37

when PD-1 is activated, what does it inhibit?

Answer 37

ZAP-70

Question 38

Therapeutic protocols have been designed around blocking the _____ binding site
to treat certain cancers and have included commercial antibodies anti-PD1 and anti-CTLA4.

Answer 38

PD-1

Question 39

what are some plant based products that can non-specifically stimulate T cells?

Answer 39

Concanavalin A (Con A) and phytohemagglutinin (PHA)

Question 40

what does Pokeweed mitogen (PWM) stimulate?

Answer 40

T cells, B cells and monocytes/macrophages.

Question 41

what does PMA target and activate?

Answer 41

protein kinase C (PKC) and ionomycin is a calcium ionophore

Question 42

Con A, PHA and PWM are quite mitogenic at concentrations in the g/mL
range, whereas PMA and ionomycin are highly mitogenic at ng/mL and pg/ml,