CHP 8 EXAM

function of Th1 cells (a) activate macrophages (b) enhance neutrophil response (c) activate cellular and antibody response to parasites (d) activate B cell maturation of antibody response (e) suppress other effector T cell

(a) activate macrophages

function of T reg cells (a) activate macrophages (b) enhance neutrophil response (c) activate cellular and antibody response to parasites (d) activate B cell maturation of antibody response (e) suppress other effector T cell

(e) suppress other effector T cell

The co-stimulatory molecule _____ on professional antigen-presenting cells binds _____ on the surface of naive T cells. A) ICAM-1; LFA-1 B) MHC class II; T-cell receptor C) B7; CD28 D) MHC class II; CD4. E) DC-SIGN; ICAM-3

C) B7; CD28

Binding of _____ to _____ induces T-cell proliferation and differentiation of activated T cells. A) IL-2; the low-affinity IL-2 receptor. B) LFA-1; ICAM-1 C) IL-2; the high-affinity IL-2 receptor D) CD4; MHC class II E) CD28; B7

C) IL-2; the high-affinity IL-2 receptor

Which of the following describes an activated dendritic cell upon arriving in a lymph node? A) located in follicles and medulla of the lymph node B) carries out apoptosis of lymphocytes. C) bears highly elaborated finger-like processes called dendrites D) expresses low levels of MHC class II molecules E) associated mainly with antigen uptake and processing in the lymph node

C) bears highly elaborated finger-like processes called dendrites

When do antigen presenting cells express B7 on their surfaces? A.Always B.Only if a Th cell binds to it C.Only if there is an infection going on D.Only before it has been activated by antigen

C.Only if there is an infection going on

Which type of T helper cell is essential for B cell activation in the lymph node? A.Th1 B.Th2 C.Tfh D.Th17 E.Treg

C.Tfh

T helper cells become anergic if they bind to an antigen presenting cell __________. A.That doesn't express CD28 B.That doesn't express MHC-II C.That doesn't express B7 D.That expresses MHC-I

C.That doesn't express B7 This is a way to deactivate self-reactive T cells that have escaped negative selection in the thymus, since an APC lacking B7 is only displaying self- peptides, not antigen peptides (or else it would be expressing B7 as well).

Which of the following cell-adhesion molecules are present on the endothelium of high endothelial venules (HEVs)? (Select all that apply.) CD34 L-selectin GlyCAM-1 ICAM-1 LFA-1

CD34 GlyCAM-1 ICAM-1

When a B cell becomes activated by antigen through its BCR, it takes up, processes and presents MHC-II-antigen to Tfh cells in the lymph node. The Tfh cell binds to the MHC-II-antigen and releases ______________ which results in the full activation of the B cell to the a plasma cell. NFK-beta Zap-70 CD40L serlysin

CD40L

All of the following statements regarding interleukin-2 (IL-2) or its receptor are true except _____. A) T-cell proliferation occurs upon binding of IL-2 to the high-affinity IL-2 receptor. B) IL-2 production increases approximately 100-fold if a co-stimulatory signal is delivered. C) The high-affinity IL-2 receptor is assembled after T-cell activation. D) The low-affinity IL-2 receptor is a membrane-bound heterodimer composed of α and β chains.

D) The low-affinity IL-2 receptor is a membrane-bound heterodimer composed of α and β chains.

Naive B cells search for specific antigen displayed by follicular dendritic cells in primary follicles. Naive T cells, however, search for specific antigen presented by ______. A) tingible body macrophages. B) medullary sinus macrophages C) subcapsular sinus macrophages D) dendritic cells E) centrocytes

D) dendritic cells

T cells failing to encounter specific antigen leave lymph nodes via the _________. A) afferent lymph B) high endothelial venules C) germinal center D) efferent lymph E) bloodstream

D) efferent lymph

T cells failing to encounter specific antigen leave lymph nodes via the _________. A) afferent lymph B) bloodstream C) germinal center D) efferent lymph. E) high endothelial venules

D) efferent lymph.

The area of contact between membranes of a T cell and an antigen-presenting cell where a clustering of protein- protein interactions occur is called a(n) _________. A) immunoreceptor tyrosine-based activation motif (ITAM) B) granuloma C) cross-presentation center D) immunological synapse. E) polarization

D) immunological synapse

The release of lytic granules from cytotoxic T cells is aimed specifically at infected target cells while preserving the integrity of neighboring, uninfected cells. This is best explained by the observation that _____. A) the amount of cytotoxins in a given cytotoxic T cell is so limited that only the cell closest to the T cell will succumb to the effects of perforin and granzyme B) uninfected cells are highly resistant to the effects of cytotoxins. C) regulatory T cells deliver survival signals to uninfected neighboring cells that renders them resistant to cytotoxins D) redistribution of lytic granules in the T cell delivers them to confined areas on the target cell in contact with the T cell E) only target cells bearing appropriate peptide:MHC class I complexes are susceptible to necrosis

D) redistribution of lytic granules in the T cell delivers them to confined areas on the target cell in contact with the T cell

After CD4 T cell activation, proliferation and differentiation occur to produce effector T helper cells. The type of T helper cell that develops depends mostly on _________. A) whether both signals 1 (TCR/MHC) and 2 (B7/CD28) were activated B) levels of ZAP70 C) the location of the T helper cell in the lymph node at the time it is activated D) the cytokine environment that the cell is in at the time of its activation and proliferation E) the level of high affinity IL-2 receptor that the cell expresses

D) the cytokine environment that the cell is in at the time of its activation and proliferation

Which of the following statements is FALSE regarding CD8 T cells? A) The most potent antigen-presenting cell for naive CD8 T cells to become activated is the dendritic cell. B) CD8 T cells have only one effector function, which is cytotoxicity. C) Compared with naive CD4 T cells, naive CD8 T cells have more stringent requirements for co-stimulatory activity. D) CD8 T cells store cytotoxins in lytic granules, which can be repeatedly replenished. E) Effector CD8 cells require co-stimulatory signals such as from IL-2 or B7 to kill their target cells.

E) Effector CD8 cells require co-stimulatory signals such as from IL-2 or B7 to kill their target cells. IL-2 not B7

If a non-professional antigen-presenting cell that lacks co-stimulatory molecules presents peptide:MHC complexes to a T cell specific for that peptide, then _____. A) the T cell begins to express the alpha chain of the IL-2 receptor. B) the T cell delivers a signal to the non-professional antigen-presenting cell to activate the expression of co-stimulatory molecules. C) the T cell differentiates into a TH1 cell. D) the T cell relies on signals transmitted through CD4 or CD8 in order to become activated. E) T-cell tolerance occurs as a result of anergy.

E) T-cell tolerance occurs as a result of anergy.

Which of the following describes an activated dendritic cell upon arriving in a lymph node? A) carries out apoptosis of lymphocytes. B) expresses low levels of MHC class II molecules C) associated mainly with antigen uptake and processing D) located in follicles and medulla of the lymph node E) bears highly elaborated finger-like processes called dendrites

E) bears highly elaborated finger-like processes called dendrites

If a non-professional antigen-presenting cell that lacks co-stimulatory molecules presents peptide:MHC complexes to a naïve T cell specific for that peptide, then _____. A) the T cell delivers a signal to the non-professional antigen-presenting cell to activate the expression of co-stimulatory molecules. B) the T cell differentiates into a TH1 cell. C) the T cell begins to express the α chain of the IL-2 receptor. D) the T cell is more heavily reliant on signals transmitted through CD4 or CD8 in order to become activated. E) the T cell becomes anergic

E) the T cell becomes anergic

How do Th cells deliver their cytokine and activation signals specifically to their target cells (macrophages in this case), and not to other cells that are nearby? A. Cytokines are delivered to the macrophage directly by secretory vesicles that cross the immunological synapse. B. The intended target cells are the only ones that have the correct receptors for the cytokines being secreted by the Th cell. C. Prolonged binding occurs only with macrophages that present the correct antigen to the Th1 cell. D. A and B are correct E. A and C are correct

E. A and C are correct

T/F only T cells express B7, and it express constitutively.

F. 1. DCs, macrophages and B cells are the only cells that express B7, 2. and only when there is an infection in progress, and they are actively processing and presenting antigen.

(T/F) CD8 T cells can only kill one cell, like neutrophiles

F. CD8 T cells can kill multiple infected cells, and they re-load their lytic granule arsenal after each attack! After the target cell begins to die by apoptosis, the T cell detaches, synthesizes new granules and moves on to the next infected cell.

T/F Mature naive T cells travels to only one lymph node to get activated. if it does not get activated, it undergoes apoptosis.

F. Mature naïve T cells may travel through multiple lymph nodes before becoming activated. If they do not get activated by either of the lymph nodes, Eventually they will re-enter the blood, and then begin the process of recirculation all over again. During an infection, the chance of a pathogen-specific naïve T cell finding an antigen that it can bind to is 1 in a million. So, a naïve T cell can travel for years in the circulation, going in and out of the lymph nodes and lymphatic vessels, until it finds a match.

T/F Dendritic cells can only process and present MHC-II

F. These versatile dendritic cells can process and present antigen in either MHC-I or MHC-II contexts so that both CD4 or CD8 T cells can respond.

T/F IL-2 binds to the high affinity IL-2 receptor in an paracrine fashion, which triggers T cell proliferation.

F. autocrine fashion ( IL-2 bind to its own receptor)

Adaptive immune response are initiated at ____________.

secondary lymphoid tissues --- lymph nodes, the spleen, and mucosal secondary lymphoid tissues of the respiratory, gastrointestinal, and reproductive tracts.

Once a naive Th cell has been activated, it begins to produce cytokine _________, and the high affinity receptor _________. IL-7 ; IL-7R IL-6 ; IL-6 R IL-10 ; IL-10 R IL-2 ; IL-2R

IL-2 ; IL-2R

CD8 T cell activation via MHC-I may require the additional _______provided by a ________that is bound to the same DC via MHC-II.

IL-2, CD4 T cell

Naïve T cell activation turns on the ______ genes, as well as those of the _________ receptor.

IL-2, high affinity IL-2

naïve T cells bind transiently to many dendritic cells, to "test out" their binding affinity for the MHC-peptide complex the DC is presenting. what happens after if it is a good match?

If the binding is a good match: then conformational changes in the LFA-1 stabilize binding and the TCR signals the T cell to begin activation and proliferation.

All of the following molecules are located in the immunological synapse cSMAC area EXCEPT: CD4 or CD8 LFA-1 TCR CD28

LFA-1

during the kill process by cytotoxic T cells,___________ _____________ triggers the activation of ____________ that cut the target cell's DNA into fragments.

serine proteases, nucleases

what are the Two signals are required for full T cell activation?

Signal 1. TCR-MHC binding and co-receptor binding (CD4-MHC-II) to stabilize the TCR-MHC complex. Signal 2. CD28-B7 binding is required for T cell activation, proliferation, differentiation and survival. CD28-B7 binding is called a co-stimulatory signal.

What is the main signal leading to dendritic-cell activation delivered by? - receptor mediated endocytosis - TLR - T cells

Signals from Toll-like receptors responding to pathogen constituents alter the expression of many genes in the dendritic cell that lead to its activation. Dendritic cells express all of the Toll-like receptors except TLR9, allowing the detection of a wide range of pathogens at sites of infection.

ZAP-70 is essential for activation of T cell signaling pathways to produce transcription factors NFKB, NFAT and AP-1 which are needed for _______________________

T cell proliferation and differentiation into effector cells.

T/F Each subset of T cells secretes a different set of cytokines which can have autocrine or paracrine effects.

T.

T/F when a dendritic cell-Tcell pair is formed, its clonal progeny of the T cell also bind to the same Dendritic cell.

T. Binding can last for days, and all clonal progeny of the T cell also bind to the same DC.

which Th subtypes enhance neutrophil response?

TH17 cells

which Th subtypes activate cellular and antibody response to parasites?

TH2 cells

How are dendritic cells protected from cytotoxic T cells that they activated?

Treg cells bound to the same DC suppress the Tc cytotoxic response. Once the Tc cells are out of the lymph node, they will attack all infected cells.

At what location does dendritic cells present antigens to T cells?

at cortex of Draining Lymph Node

What is the Dendritic Cell -T cell pair called?

cognate pair

The ____________ ______________ is a localized region where the membrane proteins of the two cells are interacting.

immunological synapse

Activation of a naïve B cell by a Tfh cell - occurs in the _________

lymph node

If circulating T cell that enter lymph node at HEV does not encounter professional antigen presenting cells like DCs or macrophages, where does it exit ?

via the efferent lymphatic vessel.

Upon initial activation of a naive Th cell by a dendritic cell, all of the following occur EXCEPT: - Lyk phosphorylates the ITAMS of the zeta-chain and CD3 - CD4 binds to the MHC-II molecule, which brings the CD4 cytoplasmic tail near to CD3 and zeta-chain cytoplasmic regions - CD4 phosphorylates the TCR cytoplasmic domains - Zap-70 activates genes needed for cell proliferation and differentiation - Zap-70 binds to phosphorylated zeta-chain ITAMS - Zap-70 gets phosphorylated (and activated) by Lck

- CD4 phosphorylates the TCR cytoplasmic domains

When the Th cell TCR binds MHC-II-antigen on macrophages, it releases __________________ molecules that stimulate the macrophage to increase phagocytosis and intracellular killing of pathogens. - IL-2 and IL-1beta - IL-10 and TNF-alpha - CD40-L and IFN-gamma - IL-6 and CXCL7

- CD40-L and IFN-gamma

Tc cells initiate cell killing of infected cells by doing all of the following EXCEPT: - Tc TCR binds to target cell MHC-II-viral antigen - Tc releases lytic granules into the synapse between it and the target cell, which induces apoptosis in the target cell - Tc undergoes cytoplasmic polarization which aims the Golgi and lytic granules toward the target cell - Tc binds to target cell with non-specific adhesion molecules

- Tc TCR binds to target cell MHC-II-viral antigen

Some Tc cells that become activated to MHC-I-viral antigens on a virus-infected DC can produce enough IL-2 to activate themselves fully to effector cell status. Other T cells require additional IL-2 that is produced by _______________. - B cells that have become infected by the same virus - macrophages that have become infected by the same virus - a Th cell that has become activated by binding to MHC-II-virus antigen on the same DC - the virus-infected dendritic cell

- a Th cell that has become activated by binding to MHC-II-virus antigen on the same DC

If there is an injury in the tissues (such as getting a cut), resident dendritic cells do all of the following EXCEPT: - activate naive T cells residing in the tissues - migrate to the nearest lymph node - phagocytose pathogens - change their morphology so that dendrites become more extensive, and surface area becomes more accessible to cells binding MHC molecules - process and present antigens

- activate naive T cells residing in the tissues they have to activate T cells at lymph node

What happens to a naive T cell that binds to an MHC-II-antigen presenting cell (APC) that is NOT expressing B7? What happens to that same T cell if it subsequently binds to an identical MHC-II-antigen on another cell that IS expressing B7? - it becomes anergic ; it gets activated - it becomes anergic ; it stays anergic - it undergoes apoptosis ; it gets activated - it proliferates ; it becomes an effector cell

- it becomes anergic ; it stays anergic

All of the following occur when a naive Th cell binds to antigen presented by a dendritic cell in the lymph node EXCEPT: - the Th cell's ICAM-1 molecule changes conformation and binds to LFA-1 molecule on the DC - the Th cell's CD4 receptor binds to the side of the MHC-II molecule - the TCR binds to the MHC-II-peptide antigen molecule on the DC surface - the two cells interact in the T cell area of the lymph node - the Th cell's CD28 co-receptor binds to B7 on the DC (which only expresses B7 if there is an actual infection and it has been activated)

- the Th cell's ICAM-1 molecule changes conformation and binds to LFA-1 molecule on the DC

Naive recirculating T cells enter lymph nodes in all of the following ways EXCEPT: - via the draining lymphatics from the injury site in the tissues - via the afferent lymphatics - via the blood and HEV - from the efferent lymphatics that leave from an upstream lymph node

- via the draining lymphatics from the injury site in the tissues

Can dendritic cells present viral antigens to T cells in via MHC-II molecules? - yes - if they are taken up by the DC via macropinoctosis - no only through cross-presentation - no - only via MHC-I - yes - if they are taken up via receptor-mediated endocytosis

- yes - if they are taken up by the DC via macropinoctosis

The CD8 T cells kill infected cells by secreting the ________ and focusing delivery of cytotoxins onto the target cell surface, focused on the area of the ____________

lytic granules, synapse

Nonspecific ingestion by phagocytes of relatively large volumes of extracellular fluid, which may contain bacteria or virus particles is called _________

macropinocytosis

how does Th cell to activate macrophage?

1. CD4-Th1 cell binds to its antigen-specific MHC-II complex on the macrophage. 2. CD40 ligand on the T cell binds to the CD40 receptor on the macrophage 3. Th1 cells secrete IFNγ which binds the macrophage IFNγR and increases the rate of phagosome-lysosome fusion. This stimulates the release of microbicidal agents to increase killing of intra-vesicular pathogens.

Clustering of the receptors in the SMAC results in activation of intracellular signaling pathways. Describe the steps pathway:

1. CD4/ CD8 activates Lck 2. Lck phosphorylates ITAM in CD3 and ζ 3. ZAP-70 binds to phosphorylated ζchain ITAM 4. Lck phosphorylates ZAP-70

Name the 4 stages on How T cells leave the blood circulation in the HEV and enter the lymph node?

1. Rolling adhesion 2. Loose binding 3. Tight binding 4. Diapedesis

All of the following are true EXCEPT: A) All animals have a Bursa of Fabricius but it is largest in birds. B) Clonal expansion of an activated T cell is stimulated mainly by the autocrine function of cytokine IL-2. C) Th1 cells activate cognate macrophages by secreting IFN-gamma; Tfh cells activate cognate B cells by secreting CD40L. D) Cytotoxic T cell delivery of the apoptotic signals to a target cell takes a few minutes. E) A naïve T cell can travel for years in the circulation, going in and out of the lymph nodes and lymphatic vessels, until it finds a match.

A) All animals have a Bursa of Fabricius but it is largest in birds.

For an activated B cell to receive survival signals and differentiate into a plasma cell, all of the following have to occur EXCEPT: A) It has to find its conjugate Tfh cell in the mantle of the germinal center. B) It has to have proliferated as a centroblast in the dark zone. C) It has to bind tightly to the intact antigen that initially activated it, which is being presented by FDCs in the light zone. D) It has to have been stimulated by Tfh CD40L which triggers AID induction, somatic hypermutation and isotype switching. E) It has to keep its cognate Tfh conjugately attached to itself

A) It has to find its conjugate Tfh cell in the mantle of the germinal center. (lymph node)

B cell and T cell cognate interaction (and formation of a conjugate pair) involves all of the following EXCEPT: A) MHC-I antigen presentation by the B cell which is recognized by the TCR of the T cell B) MHC-II antigen presentation by the B cell which is recognized by the TCR of the T cell C) CD40-CD40L binding D) Release of cytokines from T cell at the synapse E) ICAM-1-LFA-1 binding

A) MHC-I antigen presentation by the B cell which is recognized by the TCR of the T cell

The co-stimulatory molecule _____ is expressed on professional antigen-presenting cells only during active infection, and binds _____ on the surface of naive T cells. A) DC-SIGN; ICAM-3 B) B7; CD28 C) ICAM-1; LFA-1 D) MHC class II; T-cell receptor E) MHC class II; CD4.

B) B7; CD28

All of the following statements are true except __________. A) All progeny of an activated T cell bind to and become stimulated by the same DC that activated the original T cell B) T cells enter the lymph node at the HEV in response to an antigen gradient C) T cell homing occurs through a process that is similar to the extravasation seen when neutrophils leave the circulation and enter the tissues D) T cells that bind to an antigen presenting dendritic cell that also involves binding of LFA-1 to ICAM-1 are called a cognate pair E) It takes several days for a clonal expansion of T cells to become fully activated.

B) T cells enter the lymph node at the HEV in response to an antigen gradient

The area of contact between membranes of a T cell and an antigen-presenting cell where a clustering of protein- protein interactions occur (pSMAC and cSMAC) is called a(n) A) immunoreceptor tyrosine-based activation motif (ITAM) B) immunological synapse C) cross-presentation center D) polarization E) granuloma

B) immunological synapse

Cytotoxic T cells' mechanism of killing infected cells resembles that of ___________ in the innate immune response. A. macrophages B. NK cells C. neutrophils

B. NK cells