BIOL4278 Immunology

Dendritic cells present virus-specific peptides to_____________effector T cells________ secreted by these cells acts directly on the naive___________ T cell that is interacting with the same dendritic cell. These interactions provide the necessary boost for activating_________ CD8 T cells, leading to proliferation and differentiation of a virus-specific CD8 T cell to form a clone of cytotoxic T cells.

1. CD4 2. IL-2 3.CD8 4.effector

Dendritic cells take up antigens at a site of infection and carry them to a draining lymph node for presentation to naive T cells. Watch the animation on dendritic cell migration and then arrange the following steps of dendritic cell activation and migration in the correct order.

1. Dendritic cells migrate 2. using pattern 3. engagement 4. during the process of maturation 5. lymphatic fluid carries 6. T cells inspect

Complete the passage with the terms provided.

1. IgE 2. mast cells 3. TH2 4. IL-4

The T-cell co-stimulator ICOS is a protein on the surface of________cells that binds to ________ on ________

1. TFH 2. ICOS ligand 3. dendritic cells

At the site of infection, immature dendritic cells are activated through interaction of their receptors such as_______ with pathogen constituents. Migrating dendritic cells are induced to leave the lymph and enter a secondary lymphoid tissue by___________acting on __________Mature or activated dendritic cells lose their ability of _________ but gain the capacity of_________

1. Toll-like receptors 2.the chemokine CCL21 3.the receptor CCR7 4.phagocytosis 5.activation of naive T cells

Many cytokines signal through a pathway in which an intracellular protein phosphorylates and activates a transcriptional activator. The process of cytokine signaling begins with cytokine binding to its receptor, thereby dimerizing the

1. cytokine receptor 2. JAK 3.STAT 4.nucleus

The process by which naive T cells leave the bloodstream and enter the T-cell zone of a lymph node is called_____________ This process of T cells is guided by chemokines CCL21 and______ which are secreted by stromal cells and dendritic cells in the____ area. These cytokines are bound to the surface of_______ where they establish a concentration gradient along the endothelial surface. Naive T cells express the chemokine receptor_______ which binds to chemokines and causes the T cells to be guided up the chemokine gradient and toward its source in the lymph node.

1. homing 2.CCL19 3. T cell 4. high endothelial venules 5. CCR7

Activation of naive T cells requires the signal delivered by a peptide:MHC molecule complex binding to the antigen receptor TCR and CD4/8 co-receptor. In addition to this first signal, naive T cells require a co-stimulatory signal delivered by - expression of_____ on the surface of an antigen-presenting cell that is recognized by a co-stimulatory receptor_____ on the surface of T cells, thereby leading to____ of T cells

1. induced 2. B7 molecule 3. CD28 4. proliferation

Immature T cells called______undergo development in the________ Once there, the immature T cells travel outward to the_____ and progressively move back inward to the_____throughout their development. Unlike______lymphoid organs, the_______is the only route in or out of this organ.

1. thymocytes 2. thymus 3. cortex 4.medulla 5.secondary 6.blood

Naive T cells that have left the______Naive T cells that have left the_____are activated by antigen on_____in the area of the lymph node called the

1. thymus 2.arterial blood 3.dendritic cells 4.cortex

After activation by a specific antigen and as part of their differentiation taking place at_______ CD8 T cells synthesize_____ that are packaged into membrane-bound lytic granules. Effector CD8 T cells then migrate to the ____________ o exert their action on target cells. Because of their antigen specificity, cytotoxic T cells focus granule secretion at the__________ One cytotoxic T cell can kill many infected cells in succession.

1.secondary lymphoid tissue 2. cytotoxins 3. site of infection 4. target-cell surface

What is the term for a state of nonresponsiveness to antigen?

Anergy

What is associated with activated macrophages?

Associated with Activated Macrophages increased synthesis of oxygen radicals. pathogen killing by hydrolytic degradative enzymes. more efficient fusion of phagosomes with lysosomes. production of nitric oxide (NO). changes in gene expression.

Which of the following are associated with the thymus?

Associated with the Thymus colonization by bone marrow-derived dendritic cells and macrophages. T-cell development. formation of a network of epithelial cells

What best describes linked recognition?

B cells and T cells specific for different epitopes of the same antigen cooperate

Relaxation of the requirement for interaction between _____ and _____ enables CD8 T cells to kill any type of virus-infected cell.

CD28;B7

Match each cytokine or cytotoxin with the correct effector T cell that produces it. Some cell types may have more than one correct answer and some cytokines/cytotoxins may need to be matched to more than one cell type.

CD8 T cells : IFN-γ, lymphotoxin and perforin TH17 cells:IL-17 TH2 cells::TGF-β, IL-10 and IL-4 Treg cells : IL-10 and TGF-β TH1 cells : IFN-γ and lymphotoxin

What is not required to activate a naive T cell?

CTLA4

Which of the following are correct statements regarding the cytokine interleukin-2 (IL-2)?

Correct Answer(s) IL-2 acts as an autocrine cytokine. The synthesis of IL-2 requires the transcription factor NFAT. Co-stimulation increases its synthesis by about 100-fold. It is needed for proliferation and differentiation of T cells.

Which of the following are correct statements about Treg cells?

Correct Answer(s) In the presence of TGF-β, naive CD4 T cells undergoing activation can commit to the Treg cell lineage. Some Treg cells commit to regulatory function during thymic development. Treg cells play an important role in minimizing secondary infections.

During the maturation of dendritic cells, a number of changes in form and function occur. Which of the following are correct statements about these changes?

Correct Answer(s) They interact extensively with naive T cells in the cortex of secondary lymphoid tissue. They express large numbers of peptide:MHC molecule complexes at the cell surface. They form highly elaborate dendrites.

Which of the following are correct statements about potential outcomes of virus-derived peptides that are processed by dendritic cells via the endocytic pathway?

Correct Answer(s) Viral peptides are presented by MHC class I molecules by cross-presentation after their delivery to the endoplasmic reticulum. Viral peptides are presented by MHC class II molecules after they intersect the endosomal route of transport to the cell surface

What is used to divide effector T cells into their functional classes?

Correct Answer(s) the transcription factors they express, which control different differentiation pathways. the cytokines that influence their activation and differentiation their function in adaptive immunity the types of cytokines they secrete

Cytotoxic T cells kill their target cells by inducing apoptosis or programmed cell death. What are advantages of apoptosis over necrosis?

Correct Answer(s) Cells killed by apoptosis do not lyse or disintegrate. Apoptosis prevents release of pathogen from the infected cells. During apoptosis, the breakdown of viral nucleic acids prevents the assembly of infectious viral particles.

What is associated with cells undergoing apoptosis?

Correct Answer(s) DNA fragmentation increased cytochrome c in the cytosol blebbing of the plasma membrane increased permeability of the plasma membrane

Which of the following are correct statements about the discharge of cytotoxic granules by CD8 T cells onto the target cell surface?

Correct Answer(s) Initial encounter and nonspecific adhesion between the CD8 T cell and the target cell do not lead to killing of a target cell. Granule release is focused at a small, localized area of the synapse

In order for LFA-1 to bind strongly to ICAM-1 on high endothelial venules (HEVs), what must occur?

Correct Answer(s) It must become activated by the actions of chemokines secreted by endothelial cells. It must change its conformation.

Which of the following are correct statements about Treg-cell function?

Correct Answer(s) Treg-cell function involves interaction with dendritic cells. Treg-cell function is necessary to sustain life. Treg-cell function involves contacting effector T cells.

What are the outcomes of T-cell activation?

Correct Answers activation of naive pathogen-specific B cells. activation of macrophages. proliferation of naive T cells. cellular differentiation into effector T cells

Which type of bone marrow-derived cell collects pathogen antigens at the site of infection and delivers them to secondary lymphoid tissues?

Dendritic cells

What forms a dimer during cytokine-induced signaling?

Form Dimers signal transducers and activators of transcription (STATs) Janus kinases (JAKs) cytokine receptor subunits

What cell-adhesion molecules are present on the endothelium of high endothelial venules (HEVs)?

Found on HEVs GlyCAM-1molecules CD34 ICAM-1

Watch the animation on lymphocyte trafficking and then match each answer choice with the correct adhesion molecule or chemokine receptor.

ICAM-1 = LFA-1 Correct label:LFA-1 CCR7 = CCL21 L-selectin = GlyCAM-1

Although not all nucleated cells express MHC class II molecules, they can be induced to do so at sites of infection by which of the following?

IFN-Y secreated by NK cells and effector T cells

Individuals with lepromatous leprosy are often placed on a regimen of what in an attempt to reduce the lesions associated with this condition?

IFN-y

What cytokine is expected to predominate in lesions analyzed from an individual with the tuberculoid, rather than the lepromatous, form of leprosy?

IFN-y

Where are adaptive immune responses initiated?

In secondary lymphoid tissue

The innate immune response to intracellular infections involves activation of macrophages and NK cells, which in turn induced TH1 CD4 T-cell differentiation through the secretion of which cytokines?

Induces TH1 CD4 T Cells IFN-γ IL-12

What is involved in shaping the effector CD4 T-cell response?

Involved in Shaping Effector T-Cell Response tissue of origin of the activated dendritic cell. cytokines made during the innate immune response. the nature of the pathogen.

LFA-1 on naive T cells facilitates their homing to lymph nodes. What is another function of LFA-1 on naive T cells?

It promotes the formation of conugate paird with dendtitic cells

Match each label with its most proximal activation target.

PKC-θ DAG NFAT calcineurin Fos Ras PLC-γ ZAP-70

When antigen is recognized by naive T cells, why do T cells ignore the chemotactic gradient of sphingosine 1-phosphate (S1P)?

T cells that recognize antigen are induced to express CD69

In what ways does T-cell development differ from B-cell development?

T-Cell Development Only Developing T cells form two lineages distinguished by different types of T-cell receptors. T cells develop in the thymus.

Match each term with the correct description.

T-cell synapse : the complete area of localized contact and communication between a T cell and an antigen-presenting cell

Match each master regulator of differentiation with the correct effector CD4 T cell.

TH1 = T-bet TFH = Bcl6 TH2 = GATA3 Treg = FoxP3

What effector T cell does not act at an infected site outside lymphoid tissue?

TfH

What is the rationale for including an adjuvant in a vaccine?

The microbial components of the adjuvant induce-co stimulatory activity in dendritic celss

Match each effector CD4 T cell with the correct cytokine that induces its differentiation. Some cytokines may be used more than once and some CD4 T cells might have more than one correct answer.

Treg =TGF-β TH17= TGF-β, IL-6 TH2 = IL-4 TH1 = IFN-γ

What is the most effective way that B cells obtain antigen for the purpose of antigen presentation to TFH cells?

Using surface immunoglobulin as endocytic

Activated endothelium expresses which adhesion molecule, of key importance for recruiting effector T cells to inflamed tissue?

VCAM-1

What cell-surface molecule ensures that effector T cells home to infected tissues?

VLA-4

Match each CD4 T-cell subtype with its correct function.

activates macrophages, B cells, and neutrophils : suppresses effector T cells: Treg activates responses to parasites:: TH2 activates macrophages: TH1 enhances the neutrophil response: TH17 promotes B-cell differentiation into plasma cells: TFH

Other than from the blood, through which other structure can naive T cells enter lymph nodes?

afferent lymphatic vessels

Why do self-reactive T cells encountering self antigen in the periphery usually enter a state of T-cell anergy?

because the cells presenting the self antigen does not exoress B7

What does expression of CXCR5 by TFH cells enable them to do?

bind to CXCL13 and migrated toward the b-cells areas in ......

When a virus-infected dendritic cell alone is insufficient to activate a naive CD8 T cell, what must the CD8 T cell do in order to become activated?

bind to iL-2 secreted by a virus specific effector CD4 T cell

What must occur in macrophages in order for them to become activated?

binding of CD40 and the IFn-y receptor to their ligands

How do the inhibitory proteins called suppressors of cytokine signaling (SOCS) facilitate their suppressive effects?

by binding to and blocking phosphorylated tyrosine residues on cytokine receptors and janus kinases

Match each term with the correct description.

central supramolecular activation complex: area in which T-cell receptor (TCR), co-receptor, co-stimulatory, adhesion, and signaling molecules segregate

Circulating naive T cells gain access to lymph nodes through high endothelial venules (HEVs), which are located where?

cortex

What is the name given to the type of protein made by T cells that kills a target cell?

cytotoxin

In the lymph node, what is the primary role of macrophages?

filter the lymph

What is the end effect of the cytokines released by effector T cells on their target cells?

gene expression

What clinical feature is characteristic of lepromatous leprosy?

hypergammaglobulinemia

Match each term with the correct description.

immunoreceptor tyrosine-based activation motif (ITAM) : amino acid sequence on CD3 components and ζ chain where phosphorylation occurs

The fully human monoclonal antibody secukinumab is an FDA-approved biologic for the treatment of plaque psoriasis and other autoimmune disorders in adults in which self-reactive TH17 cells cause tissue damage. The monoclonal antibody has specificity for interleukin 17A (IL-17A), a member of the IL-17 family. What is consistent with the mode of action of this therapeutic agent?

inhibition of neutrophil chemotaxis

What is true regarding a T cell that has been rendered anergic?

it can not be revived, even if co-stimulation is provided.

What is the consequence of an absence of functional ZAP-70 in T cells?

no signal is transimitted onward from the t cells receptor complex

Cytotoxic CD8 T cells are selective and serial killers of target cells at sites of infection. The killing of infected target cells by effector CD8 T cell is initiated by which molecular interaction at the surface of cells?

peptide-MHC complex on surface of infected cells recognized by tcr-cd8 complex

Match each term with the correct description.

peripheral supramolecular activation complex : area in which integrins, adhesion molecules, and cytoskeletal proteins segregat

What is the term for when TH1 or TH2 cells dominate as a result of cytokine-driven positive feedback?

polarized response

Unlike the cytotoxins made by CD8 T cells, cytokines made by CD4 T cells differ in what way?

they are not performed and stored in granules in the cytoplasm.

What characteristic defines anergic T cells?

they are unable to produce iL-2

What is the fate of naive T cells that encounter their specific antigen in a lymph node?

they proliferate and differentiate into effector T cells before leaving the lymph node via an efferent lymphatic.

What delivers the main signal leading to dendritic cell activation?

toll-like receptors