Immunology 10 - T Cell Effector Functions

Front 1

What are 4 effector functions of T Cells?

Back 1

1. Production of cytokine
- recruit and activate cells of innate immune system
- stimulate proliferation and increase effector functions of other T and B cells

2. Promote antibody secretion and antibody class switching

3. Kill infected target cells

4. CD4+ cells can act as negative regulators of immune responses

Front 2

What is "cross-presentation"?

Back 2

When an APC can put an antigen that would normally be expressed on an MCH-I, on its MHC-II and activate a CD8+ CTL cell

Front 3

Once activated, what molecules allow T cells to home to the location of infection?

Back 3

Once activated, T cells shed L-selectin and express E-SELECTIN and P-SECLECTIN

- the ligands for these integrins are found in the endothelium where infection is

Front 4

Do effector CTLs need co-stimulation (2 signals) to be affect their function?

Back 4

No, ONLY need antigen/MHC I

Front 5

What two enzymes to CTLs release that kill an infected cell?

Back 5

1. Perforin - forms pore in the target cell memrane

2. Granzymes - activate capsases that make cell undergo apoptosis

Note: This mechanism leaves surround cells unharmed

Front 6

What is the main role of CD4+ Helper T cells?

Back 6

- Act mainly as recruiters and activators of other immune cell components via the secretion of cytokines

Front 7

What is the role of IL-2 with regard to T cells?

It's source?

Back 7

- T cell growth stimulation

- Source: CD4 and CD8 cells

Front 8

What cytokine's principal action is to call B cell isotype switching to IgE?

It's source?

Back 8

- IL-4

- Source: CD4 and mast cells

Front 9

What is the role of IL-5?

It's source?

Back 9

- Activation of eosinophils

- Source: CD4, CD8, and NK cells

Front 10

What cytokine is important in the activation of macrophages?

It's Source?

Back 10

- Interferon-gamma (INF-Gamma)

- Source: CD4, CD8, NK cells

Front 11

What is the role of TGF-Beta?

It's source?

Back 11

- Inhibition of T cell activation
- Also promotes IgA secretion

Source: CD4; many other cell types

Front 12

What cytokine do macrophages produce?

What is it's role?

Back 12

- IL-12

- Stimulate T cell effector differentiation
- Also stimulates NK cells

Note: Effector T cells then produce INF-Gamma which stimulate macrophages

Front 13

What subtype of T cell developes in the ABSENCE of TGF(beta) but the PRESENCE of INF(gamma)?

What is its function?

Back 13

- Th1

- Functions in combating intracelllar pathogens through its own production of TGF(beta) that stimulate macrophages

Front 14

What subtype of T cell developes in the ABSENCE of TGF(beta) but the PRESENCE of IL-4?

It's function?

Back 14

- Th2

- Functions in stimulating IgE production that's important in combation helmenthic worms

Front 15

What subtype of T cell developes in the PRESENCE of TGF(beta) and the PRESENCE of IL-6?

It's function?

Back 15

- Th17

- Function in potent pro-inflammatory cytokine that stimulates responses to counter EXTRACELLULAR pathogens

Front 16

What subtype of T cell developes in the ONLY the PRESENCE of TGF(beta)?

Function?

Back 16

- Treg cells

- Are regulatory cells that function to dampen the immune response

Front 17

What is the dominant transcription factor for:

1. Th1 cells
2. Th2 cells
3. Th17 cells
4. Treg

Back 17

1. T-bet

2. Gata-3

3. ROR-gamma

4. FoxP3

Front 18

In addtion to INF-gamma what other cytokine helps to lead T cells to become Th1 cells?

Back 18

IL-12

Front 19

What cytokines do Th2 cells produce?

Back 19

IL-4 - induces B cells to class switch to IgE

IL-5 - stimulates eosinphils to become active

Front 20

What cytokine do Th17 cells produce?

Back 20

IL-17

Front 21

What is the function of Th17 cells?

Back 21

Help in inflammatory response and recruitment of neutrophils

Front 22

Are all subsets of T cells produced at once?

Back 22

No, CD4+ T cell subsets negative regulate each other

- ex: int he absence of inflammation or an infection stimulus, regulator T cells produce TGF-beta that interferes with activation of naive T cell, thus preventing differentiation into Th1 and Th2

Front 23

Lack of co-stimulation leads to what?

Back 23

- Anergy

- Need BOTH antigen and co-stimulation (B7) to activate T cell

Front 24

What molecule competes with CD28 for access to B7?

Back 24

CTLA4

Front 25

What cytokines do Treg cell produce to downregulate T cells?

Back 25

IL-10 and TGF-beta

Front 26

What does central tolerance refer to?

Back 26

- Elimination of self reactive lymphocytes during their development

Front 27

What is the suppression of immune responses by cells which, although self reactive, have escaped deletion during development?

Back 27

Peripheral tolerance

Front 28

Once an immune response is done, engagement of what cell surface receptor activate T cell death?

Back 28

Fas/CD95

- When Il-2 and co-stimulatory signals are absent, the function of the pro-apoptotic proteins dominate

Front 29

What are two general methods by which autoimmunity can result?

Back 29

1. Induction of costimulators of APCs- if APCs interact with self T cells w/ co-stimulation, can get autoimmunity

2. Molecular mimicry - if a foreign antigen is similar enough to cause T cells to attack the similar self antigen

Front 30

What are two HLA alleles that predispose a person to autoimmunity?

Back 30

1. B27

2. DR4

Front 31

What is the gene that shows ALL self antigens to T cells in the thymus?

Back 31

AIRE - mutation in this can cause autoimmunity (APECED)

Front 32

What is Autoimmune lymphoproliferative syndrome?

How is it caused?

Back 32

- Expanded T cell population fail to be eliminated resulting in lymphadenopathy and splenomegaly

- caused by defect in Fas signaling