chapter 9 Flashcards by Madison wilder

T cells develop in ___ and then enter the bloodstream
-once they reach a secondary lymhoid organ, they leave the blood stream and migrate through lymphoid tissue, returning via lymphatics to blood

Thymus

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mature circulating T cells who have not encountered antigen are called ____

naive T cells

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Once T cells encounter an antigen with MHC, they proliferate and differentiate into cells called____

effector T cells

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Adaptive immune responses are intiated in the secondary lymphoid organs: _____

spleen, lymph nodes, MALTs (peyer’s patch in gut)

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T and B cells are partitioned into distinct regions of secondary lymphoid tissues by the actions of ____

chemokines

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what is the secondary lymphoid tissue?
-antigen free or as cargo in dendritic cell
-delivered to B cell/T cell zones
-B/T cells enter from high endothelial venules (HEV)

Lymph node

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what is the secondary lymphoid tissue?
-antigen via arterioles which branch from central arteriole to marginal sinus
-in marginal zone antigen is taken by APC to T cell zones or B cell follicles

spleen

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what is the secondary lymphoid tissue?
-antigen from lumen via microfold (M) cells to dendritic cells in subepithelial region

peyer’s patch

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circulating B and T cells come to secondary organs by common route. Then they move into distinct regions under control of ____

chemokines

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stromal cells and bone marrow derived cells in B-T cell zones produce cytokines. they produce ___.

CCL21

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dendritic cells have a receptor for CCL21. Dendritic cells migrate. They then secrete ____. this then attracts T and B cells.

CCL19

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-present in abundace at barrier tissue sites. In the absence of infection or tissue injury, they have low levels of costimulatory molecules so are not capable of activating naive T cells
-once they see antigen (in variety of ways), they pick it up, process it and present it
-mature conventional dendritic cells activate naive T cells

conventional dendritic cells

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what type of dendritic cell has a role in adaptive immunity?

Conventional

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-are sentinels for viral infections and secrete large amounts of class I interferons
-not as efficient in activating T cells
-play role in innate immune response. may help conventional cells sustain production of IL-12 which asks T cells to mak IFN-gamma

plasmacytoid dendritic cells

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conventional dendritic cells are activated through stage to become activated APCs in peripheral lymphoid tissue
-entry to the tissue is based on chemokine receptor they express
-tissue resident DCs are phagocytic via receptors such as:______

dectin, DC-sign, Langerin

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conventional dendritic cells are activated through stage to become activated APCs in peripheral lymphoid tissue
-at site of infection, TLR signaling causes them to get activated
-Induction of CCR7. cells expressing this are sensitive to ____ and ___ produced by lymphoid tissue

CCL19 and 21

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conventional dendritic cells are activated through stage to become activated APCs in peripheral lymphoid tissue
-CCR7 forces migrated of dendritic cell to lymphoid tissue
-costimulatory molecule B7 made and MHC expressed
-by the time they arrive to the lymph node, they are activators of ___, present antigen, no more phagocytosis

naive T cells

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what is the difference between conventional dendritic cell and plasmacytoid dendritic cell?

the difference is who can activate a T cell and who can not

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Macrophages are ____ that can be induced by pathogens to present foreign antigens to naive T cells

scavenger cells

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resting macrophages have few or no ___ and no ____

MHCII and B7

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____are non migrator and do not go to T cell zones

tissue resident macrophages

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macrophages in lymphoid organs (lymph node, marginal sinus) but do not activate T cells. Function is to ____.

ingest foreign agents

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macrophages and B cells present antigen primarily to receive help from effector T cells in the form of ___ or ____

cytokines or surface molecules

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where are dendritic cells found?

anywhere in the body

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where are macrophages found?

lymphoid tissue, connective tissue and body cavities

where are B cells found?

lymphoid tissue and peripheral blood

B cells are highly efficient at presenting antigens that bind to their surface ____ - the internalized antigen is processed and bind to ____.

immunoglobulin; MHC II molecules

antigen presenting cells deliver 3 signals for the clonal expansion and differentiation of naive T cells, what are the 3 signals?

activation, survival and differentiation

what occurs at these 3 signals? 1. activation ____ 2. survival ____ 3. differentiation ____

1. MHC-TCR 2. co-stimulatory molecule, allows increased proliferation and survival of T cells (here CD28 and B7) 3. Effector response by T cell depends on 3rd signal. Cytokines do this signal.

additional co-stimulatory pathways are involved in T cell activation -B7 whose receptor is ___ and ___ on T cell

CTLA-4 and CD28

-_____is an inhibitory molecule of T cells -____serves to regulate proliferative phase of T cell response

CTLA-4

____ binds B7 more avidly than does ___ and delivers inhibitory signal to activated T cells

CTLA-4; CD28

proliferating T cells differentiate into effector T cells that do not require co-stimulation to act 1. both signal received, activated, secretes and responds to IL-2. this increases expression of ___ 2. IL-2 signaling enhances ____ and contributes to differentiation of T cell effector cells 3. now any encounter with antigen will trigger___

1. IL-2 receptors 2. clonal expansion 3. action (no costimulation needed)

CD8 T cells can be activated in different ways to become cytotoxic effector cells. Because of toxic effects of CD8 T cells, they need additional activation via ___; these molecules come from dendritic cells to activate CD8 T cells to produce IL-2

stimulatory molecules

CD8 t cell activation needs help from ___

CD4 T cell

CD4 T cell: APC interaction further activates CD4 to release IL-2 which activates CD 8 T cell or dendritic cell forces T cell to activate ____ which when bound to CD40 on APC, Increases B7 production and 4-1BBBL production which activate CD8 T cell more

CD40L

IFN-gamma acts on macrophages ingestion

TH1

-goblet cells -IL-5 recruits eosinophils -IL-4 mast cell/basophil

TH2

-IL-17 induces local epithelial cells to make chemokines to bring neutrophils -also makes epithelial cells produce antimicrobial peptides -extracellular bacteria

TH17

-ready to activate a B cell -follicular helper cells

TFH cells

-kept in stage suppressing immune system don't want CD4 or CD8 -lack of T cell activation -suppress T cell and innate immune cell activity to prevent auto immunity

Treg cell

APC/dendritic cells (innate immune cells) produce ____. The environment, exposure to pathogens etc, determine which cytokines the innate sensor cells will produce

cytokines

Th1 cells differentiate in response to ____ and ___ -if no pathogen is present then, the TGF-beta and IL-2 will force the cells to differentiate into T regulatory cells

IFN and IL12

each cytokine that specifies the development of specific effector cells activates different members of the ___ family of transcription factors

STAT

1.T cell effector function involves interaction of T cell with a target cell displaying ____ 2. focusing mechanism is common to all effector cells but action is dependent on ____

1. antigen 2. type of T cell engaged

initial interaction between T cell and target cell is mediated by non specific cell adhesion molecules (like ICAMS). Allows T cell to stay in contact and then scans for ____

MHC: peptide complex

what are the functions of TH1/

1. activate macrophages 2. secret IFN-gamma to activate infected cells 3. FAS ligand activation triggers death of FAS bearing targets

___ promote response to parasites and promote allergic responses. They help B cell activation (CD40L binds CD40 on B cells to proliferate them) and secrete B cell growth factors

TH2

___ produce IL17 and IL22 acute inflammation by recruiting neutrophils to site of infection

Th17

___ act at a distance and exert inhibitory actions via cell to cell interactions

Treg Cytokines

to eliminate viruses, which are inside a cell, you need the work of ___

cytotoxic T cell

cytotoxic T cell target the infected host cell for death. cells die in a variety of ways, what are they?

necrosis and apoptosis

cell disintegration from tissue damage with antibody/complement is called __

necrosis

is a regulated process induced by extracellular signals

apoptosis

apoptosis can be __ or __

extrinsic or intrinsic

activation of death receptors by extracellular ligands

extrinsic

induced in response to noxious stimuli or lack of growth factors needed for survival

intrinsic or mitochondrial pathway

apoptosis is mediated by ___ who are protected from acting by protector proteins

executioners

the release of executioners causes the release of ___ from mitochondria and subsequent cell death

cytochrome C

release of Cyt-C is controlled by Bcl-2 proteins. there are 2 groups:

promote apoptosis and inhibit apoptosis

___ proteins are induced by stimuli that promote cell survival. These proteins bind to mitochondrial membrane and prevent the release of cyt C

anti-apoptotic

___ family proapoptotic also are sentinel proteins. they (Bad, Bil, PUMA) once activated by stimuli either block anti apoptotic proteins or directly stimulate

Bcl-2

what are the executioners

Bax, Bak, Bok

what are the protectors?

Bcl-2, Bcl-XL, Bcl-W

proteases that trigger apoptosis in target cell

granzymes

___which helps deliver granzymes to target cells

perforin

effector molecules produced are either cytotoxins or cytokines -they have FAS ligand, which binds FAS on target cell and activates _____

apoptosis

what are the cytotoxic effector molecules?

perforin, granzymes, granulysin, FAS Ligand

perforin and granzymes needed for effective target cell killing granzymes trigger apoptosis by activating ___ and by damaging mitochondria which in turn activates caspases

caspases

aids in delivering contents of granules into the cytoplasm of target cell

perforin

serine proteases, which activate apoptosis once in the cytoplasm of the target cell

granzymes

has antimicrobial actions and can induce apoptosis

granulysin

cytotoxic t cells are selective ____ of targets expressing a specific antigen

serial killers

T cells focus secretion on point of __ with target cells and move the granules to release right near the cell

contact

cytotoxic T cells can also act by releasing cytokines not just inducing apoptosis:

IFN-Gamma; TNF-alpha and LT-alpha

inhibitors viral replication directly and increases expression of MHC-I raises chance of cytotoxic attack, recruit macrophages to site

IFN-gamma

recruit macrophages, kills cells by interacting and inducing apoptosis

TNF-alpha and LT-alpha

chapter 9 Flashcards

(77 cards)