32 T cells

Question 1

This form of T cell activation generates a diverse repertoire of mature T cells

Answer 1

Antigen independent activation

Question 2

This form of T cell activation results in:

1) Activation (two signals: MHC complex + B7 binding or IL-2R activation)
2) Survival
3) Proliferation (clonal selection)
4) Differentiation into effector T cell or Memory T cell (always ready to switch to an effector T cell)

Answer 2

Antigen dependent activation

Question 3

This type of T cell activation leads to apoptosis or anergy

Answer 3

TCR-MHC2 binding only

Question 4

This type of T cell activation leads to proliferation, differentiation, and effector function

Answer 4

MHC2-TCR and CD28-B7 (CD80/86)

Question 5

This type of T cell activation leads to cell-cycle arrest

Answer 5

MHC-TCR and (CTLA-4)-B7(CD80/86)

Question 6

: IL-2 release from the CD4+ cell is a(n) ___ signal that binds to the IL-2 receptor and signals proliferation and activation.

Answer 6

Autocrine signal. Note: This is why experienced T cells have a lower threshold for activation (they already have many IL-2 receptors in the membrane)

Question 7

binds to B7 by displacing CD28, blocking IL-2 synthesis. As a result, the antigen presenting cell becomes less effective at presenting antigens to T cells, and T cell activation is inhibited (anergy is the major outcome of this)

Answer 7

Cytotoxic lymphocyte antigen-4 (CTLA-4)

Question 8

 Naïve T cells circulate through the lymph nodes and find antigens
 Activation of naïve T cells in the lymph nodes leads to development of effector cells, and clonal expansion
 These experienced T cells now have no business in the lymph nodes, and migrate to the site of infection (or other lymph nodes to meet B cells)
 Antigen presentation to experienced T cells: At the site of infection, macrophages and B cells present the antigen to experienced T cells, telling the T cells that their presence is indeed necessary there to help eliminate the infection. If the innate immune system has cleared the infection, no such signal will be received and the T cell will die

Answer 8

Activation and migration of T cells

Question 9

T cells that have not divided into a specific subtype

Answer 9

Naive helper T cells (Th0)

Question 10

subtype of T cell that is responsible for helping B cells produce antibodies (as well as assisting w/ class switching). Located in the follicles (w/ the B cells)

Answer 10

Follicular helper T cells

Question 11

Subtype of T cell that activates macrophages to deal w/ intracellular infections

Answer 11

Effector helper T cells (Th1)

Question 12

Subtype of T cell that activates neutrophils and induces inflammation

Answer 12

Effector helper T cells (Th17)

Question 13

Subtype of T cell that induces production of IgE to deal w/ parasitic infections

Answer 13

Effector helper T cells (Th2)

Question 14

Cytokines that cause Th0 cells to differentiate into Tfh cells

Answer 14

IL-6 and IL-21

Question 15

This cell gives the 2nd signal to the B cell to differentiate and produce antibodies (remember that the 1st signal is antigen phagocytosis)

Answer 15

Follicular helper T cells

Question 16

This cell type mainly deals w/ intracellular infections. I.e. microorganisms that evade the immune response and establish infections (ex: bacteria that prevent fusion of the phagosome w/ the lysosome)

Answer 16

Th1 cells

Question 17

T/F
• A macrophage gets infected w/ a bacteria, and is unable to clear the bacteria from its cytosol.
• A dendritic cell now migrates to the lymph nodes and presents the antigen of this intracellular pathogen to a Th0 cell, which differentiates into a Th1 cell.
• The Th1 cell now secretes IFN-gamma (main secretion of these cells), which enhances the ability of macrophages to destroy the intracellular pathogen

Answer 17

True

Question 18

This cell type secretes IFN-gamma and helps the B cell to produce a particular type of IgE molecule (which is good at fixing complement, neutralizing the antigen, and activating macrophages). Only effective against extracellular pathogens

Answer 18

Th1 cell (secondary function)

Question 19

IL-2, TNF-alpha, and IFN-gamma are the major secretions of which cell type?

Answer 19

Th1 cells

Question 20

Th0 cells differentiate into Th1 cells in response to which cytokine? What cell type releases this cytokine?

Answer 20

IL-12. Released by activated macrophages

Question 21

This cell type makes macrophages better at killing microbes and better at presenting antigens (in case it cannot clear the infection, it can recruit help from CD8+ cells)

Answer 21

Th1 cells

Question 22

Signaling from which cytokine released from which cell type(s) results in differentiation into Th2 cells?

Answer 22

IL-4. Released by APCs

Question 23

The major function of this cell type is stimulating production of IgE

Answer 23

Th2 cells

Question 24

T/F. IL-4 secretion from Th2 cells induces B cells to produce IgM, which binds to a parasite and induces degranulation of mast cells –killing the parasite

Answer 24

False. . IL-4 secretion from Th2 cells induces B cells to produce IgE, which binds to a parasite and induces degranulation of mast cells –killing the parasite

Question 25

IL-4, IL-13, and IL5 are cytokines secreted by which cell type and what is their function?

Answer 25

They are secretions of the Th2 cell type. Their function is to attract cells that can bind IgE (granulocytes and mast cells) and increase intestinal motility. These are anti-parasite defenses

Question 26

The major cytokine of this cell type is IL-4. Promotes differentiation of Th0 into Th2 cells. Promotes switch to IgE (and IgG) production to deal w/ parasites. Responsible for allergic reactions. Inhibits Th1 production from Th0

Answer 26

Th2 cell type

Question 27

T/F. Th2 cells mediate the response against intracellular infections

Answer 27

False. Th2 cells mediate the response against parasites

Question 28

Which cell type secretes IL-17 and IL-22?

Answer 28

Th17 cells

Question 29

This cytokineattracts neutrophils to the site of inflammation by inducing the cells of the infected tissue to secrete the inflammatory cytokines (promoting inflammation). Also increases the production of anti-microbial peptides from epithelial cells

Answer 29

IL-17

Question 30

This cytokine activates cytotoxic T lymphocytes, inducing cell death by apoptosis

Answer 30

IL-2

Question 31

T/F. A dendritic cell must migrate from the site of infection to the lymph node to present the antigen to the T cell. 1) In this case, the first thing that the dendritic cell must do is present the antigen to a naïve T helper cell. 2) The T helper cell then activates the CD8+ cell 3) Two signals for activation: 1st signal from antigen, 2nd signal from T helper cell. Both are necessary for activation (which stimulates survival, proliferation, and differentiation) 4) The CD8+ cell then differentiates into memory T cells and Cytotoxic T lymphocytes (CTLs)

Answer 31

True

Question 32

T/F. Naïve CD8+ cells emerge from the thymus. Activation requires recognition of the cognate antigen-MHC by TCR and proper co-stimulatory signals (directly by APC or Th cell)

Answer 32

True

Question 33

o Perforin/granzyme-mediated cell killing: Perforin pokes hole in the membrane. Granzyme is then injected into the cell. Granzyme activates caspases, activating apoptosis o Fas/Fas ligand mediated cell killing: The FasL on CTL surface interacts w/ the Fas receptor on the target cell, initiating the intrinsic pathway of apoptosis.

Answer 33

Mechanisms of cell death induced by cytotoxic T cells

Question 34

Defects in this cell type result in increased susceptibility to viral and intracellular bacterial infections and reactivation of latent virus infections (such as infection by the epstein-barr virus), which are normally kept in check by these cells

Answer 34

Cytotoxic T lymphocytes

Question 35

___ reactions are mediated by Th1 cells

Answer 35

Delayed type hypersensitivity reactions

Question 36

The classic inflammatory cytokines that function to recruit phagocytic cells to the site of infection

Answer 36

TNF-alpha & IL-1

Question 37

Certain B cells release this Ig isotype. The function is neutralization of the effect of the pathogen

Answer 37

IgG4

Question 38

Review diagrams

Answer 38

Do it

Question 39

Cytokines secreted by macrophages

Answer 39

TNF, IL-1, and IL-12

Question 40

This cell type enhances the killing capability of macrophages by increasing the rate of production of ROSs (ex: NO) and lysosomal enzymes

Answer 40

Th1 cells

Question 41

This cell type causes the macrophage to increase secretion of cytokines (TNF, IL-1, and IL12) and chemokines

Answer 41

Th1 cells

Question 42

This cell type causes the macrophage to increase expression of B7 and MHC in their membranes

Answer 42

Th1 cells