Chapter 8: T-Cell Mediated Immunity

dendritic cell

takes up an antigen at the primary infection site and transports it to the draining lymph nodes

outermost cortex/T cell zone

Where are dendritic cells found in lymphoid tissue?

outermost cortex/T cell zone

Where are naive T cells found in lymphoid tissue?

HEV

small capillaries that dendritic cells use to enter the lymph nodes

lightly

Is MHC class 2 lightly or heavily expressed in the lymphatic circulation? 

heavily

Is MHC class 2 lightly or heavily expressed in the lymphoid tissue?

receptor-mediated endocytosis

process that captures bacteria/virus particles in extracellular fluid and send them to lysosome

macropinocytosis

process that internalizes a larger volume of extracellular fluid directly without a receptor

true

T/F: dendritic cells can have both classes of MHC

MHC class 2

Which MHC class is used during receptor-mediated endocytosis? 

MHC class 2

Which MHC class is used during macropinocytosis? 

T cell zone

outermost part of the lymph node cortex where naive T cells meet with mature dendritic cells and respond to specific antigens

increase

The trapping of antigens in the draining lymph node increases or decreases their chance to meet the small population of T cells specific for a particular antigen? 

homing

naive T cells leave the bloodstream to enter the T cell zone of a lymph node

draining lymph node

lymph node nearest to the infection site

HEV

T cells from the bloodstream enter the lymph node through what? 

true

T/F: naive T cells enter lymph nodes via blood route or afferent lymph

L-selectin

1; an adhesion molecule that binds to GlyCAM-1 and CD34 on HEVs to attach the T cell to the endothelium to initiate migration of naive T cells into the lymph node

LFA-1

2; activated by chemokine and binds tightly to ICAM-1 to help assist in the naive T cell entering the HEV in the lymph node; part of p-SMAC

extravasation

3; process where the lymphocyte leaves the blood and enter the lymph node

conjugate pair

when 2 cells have multiple receptors required for activation

true

T/F: adhesive interactions between a naive T cell and a dendritic cell are transient but provide chances for T cells to scan through the peptide:MHC for specific recognition

true

T/F: when the T cell proliferates into a clone of effector T cells, all the clones are in contact with the dendritic cell in the process

sphingosine-1-phosphate (SIP)

forms a gradient between the T cell area and the efferent lymphatic vessel to control the process of effector T cells leaving the lymph node after the completion of proliferation

co-receptors

CD4 and CD8

CD28

1; co-stimulatory receptor on T cells that recognizes B7 on the dendritic cell surface and promotes T cell activation

B7

2; co-stimulatory ligand found on the antigen presenting dendritic cell surface that’s recognized by the CD28 co-stimulatory receptor; induced upon activation of professional antigen presenting cells

false

T/F: dendritic cells always express co-stimulatory ligands

true

T/F: dendritic cells only express co-stimulatory ligands upon activation

true

T/F: the stimulation for T cell proliferation and differentiation requires receptor, co-receptor and co-stimulatory interactions

T cell synapse

space between a naive T cell and an antigen specific dendritic cell; includes the c-SMAC and p-SMAC; also space between effector T cells and target cells

central supermolecular activation complex (c-SMAC)

1; part of T cell synapse that includes TCR, CD2, CD4, CD8, and CD28; triggers signal transduction in T cells; includes TCR complex and co-receptors and co-stimulators

peripheral supermolecular activation complex (p-SMAC)

2; part of T cell synapse that includes LFA-1, ICAM-1; triggers signal transduction in T cells

true

T/F: the clustered interactions trigger signal transduction via several tyrosine phosphorylation reactions, which lead to T cell differentiation 

interleukin-2 (IL-2) 

cytokine that acts on the activated T cell in an autocrine fashion; produced by activated T cells and is essential for the proliferation of activated T cells

false

T/F: naive T cells and activated T cells have the same forms of IL-2 receptors

lower

Naive T cells have a higher or lower affinity to IL-2? 

higher

Activated T cells have a higher or lower affinity to IL-2? 

true

T/F: naive T cells can be activated by different types of cytokines leading to differentiation into distinct effector subsets that participate in different immunological processes 

TH1, TH2, TH17, TFH and Treg

activation of naive CD4 T cells can trigger these 5 types of effector CD4 T cells

TH1 cells

effector CD4 T cell that activates macrophages to suppress intracellular infections by fusing phagosomes more efficiently with lysosomes and increasing the synthesis of microbicidal molecules, such as oxygen radicals and nitric oxide; produces inflammatory cytokines

TH2 cells

effector CD4 T cell that activates cellular and antibody response to parasites; helps basophils, mast cells, eosinophils and B cells; produce non-inflammatory cytokines that promote the production of IgE antibodies

TH17 cells

effector CD4 T cell that enhances neutrophil response to fungal and extracellular bacterial infections’ promote inflammation and are associated with autoimmune conditions

TFH cells

effector CD4 T cell that activates B cells to refine the antibody response; follicular helper T cell; helps switch isotype and increase antibody affinity; moves from the T cell area in the lymph nodes to B cell area where they interact with naive B cells in afferent lymph that have been exposed to the antigen at the site of infection

Treg cell`

effector CD4 T cell that suppresses other effector T cells

true

T/F: IL-2 production is important in CD8 T cell proliferation

true

T/F: a naive CD8 T cell can be activated directly by a virus-infected dendritic cell

true

T/F: a dendritic cell that induces insufficient co-stimulation can be helped by IL-2 secreted by the CD4 T cells to boost the activation of CD8 T cells

true

T/F: naive CD8 T cell activation requires a co-stimulatory signal

false

T/F: effector CD8 T cells/cytotoxic T cells require a co-stimulatory signal

cytokine

protein that alters the behavior of the target cell via gene regulation

cytotoxin

protein secreted by cytotoxic T cells that kills the target cell

cytotoxin

Does CD8 mainly produce cytokines or cytotoxins?

cytokines

Does CD4 only produce cytokines or cytotoxins?

helper T cell

What type of T cell is CD4?

cytotoxic T cell

What type of T cell is CD8?

granzyme

protease cytotoxin stored in lytic granules of CD8 T cells

perforin

membrane disrupting cytotoxin stored in lytic granules of CD8 T cells; forms pores in the target cell membrane

granulysin

detergent-like cytotoxin stored in lytic granules of CD8 T cells; makes pores in the target cell membrane

serglycin

proteoglycan cytotoxin stored in lytic granules of CD8 T cells

true

T/F: the targeted release of cytotoxins allows cytotoxic T cells not to attack healthy neighboring cells or the T cell itself

true

T/F: once the target cell is dying, the cytotoxic T cells can detach from the target, make a new set of lytic granules and move onto the next target cell

lytic granules

intracellular storage granule of where cytotoxins of CD8 T cells are stored

IFN-γ

cytokine secreted by activated CD8 T cells to inhibit viral replication, enhance MHC expression and activate macrophages to dispose of dead/dying infected cells

macrophage activation

the overall enhancement of macrophages by the cytokines secreted by TH1 cells

IFN-γ and CD40 ligand

two cytokines from TH1 cells that activate macrophages

true

T/F: TH2 and Treg cytokines suppress macrophage activation and limit damage to healthy cells

MHC class 2

Which MHC class goes with CD4 T cells?

MHC class 1

Which MHC class goes with CD8 T cells? 

T cell anergy

state of nonresponsiveness that’s induced in naive T cells if their antigen receptor is engaged in the absence of co-stimulation

CD40 ligand

transmembrane protein on T cells that’s the ligand for CD40 on B cells and triggers their proliferation and differentiation and their ability to switch isotypes

true

T/F: only mature dendritic cells can activate naive T cells

true

T/F: naive T cells can only be activated in secondary lymphoid tissues

false

T/F: naive T cells are activated in both the cortex and the medulla of lymph nodes

true

T/F: naive T cells express LFA-1 molecules that change their conformation after encountering a specific peptide:MHC complex

true

T/F: naive T cells exit from lymph nodes using the same route as effector T cells

true

T/F: naive T cells express S1P receptors on their surface, which allows them to reenter the circulation

false

T/F: Once T cells are activated by specific antigens, they cease to secrete and respond to IL-2

true

T/F: Once T cells are activated by specific antigens, they suppress expression of the S1P receptor

true

T/F: dendritic cells upregulate B7 after engaging innate immunity receptors at sites of infection

__ cells remain in, rather than leave, the secondary lymphoid organs in which they differentiated. 

CD4 TFH cells