AGET

Question 1

How do Tcells freely move into the lymph nodes?

Answer 1

→through high endothelial venule

Question 2

What does Tcell recirculation and acativation depend on?

Answer 2

→chemokines

Question 3

What happens if a Tcell goes to second lymph node without encountering an antigen?

Answer 3

→it goes back to circulation until it finds antigen

Question 4

What are the secondary lymphoid organs?

Answer 4

→spleen

→lymph nodes

Question 5

What does activation of naive Tcells in lymph nodes result in?

Answer 5

→development of effector cells

Question 6

What does activation of effector Tcells at site of infection result in?

Answer 6

→eradication of microbe

Question 7

What do activated dendritic cells express?

Answer 7

→high levels of MHC2

→CD80/86

Question 8

What do APCs also secrete?

Answer 8

→co-stimulatory

Question 9

What activates dendritic cells?

Answer 9

→PAMPs

→cytokines

Question 10

What factors activate macrophages?

Answer 10

→PAMPs

→Tcell help, IFN-gamma

Question 11

What do activated macrophages express?

Answer 11

→MHC1
→MHC2
→CD80/86

Question 12

What do activated B-lymphocytes express?

Answer 12

→MHC1
→MHC2
→CD80/86

Question 13

What are the three signals required for naïve Tcell activation?

Answer 13

→Antigen recognition through MHC and TCR
→Co-stimulation
→ Cytokines

Question 14

Where are most co-stimulatory signals found in naïve Tcell activation?

Answer 14

→dendritic cells

→also macrophages or Bcells

Question 15

What are two co-stimulatory signal molecules needed for Tcell naive activation?

Answer 15

→B7:CD28 interaction

Question 16

Which cell expresses CD28?

Answer 16

→Tcell

Question 17

Which cell expresses B7(CD86)?

Answer 17

→APC

→B7-1 (CD80) and B7-2 (CD86)

Question 18

How is B7 activated in dendritic cells?

Answer 18

→activated by PAMPs

Question 19

How do Tcells activate APCs?

Answer 19

→via CD40(on dendritic cells) – CD40L interaction

→T cells upregulate CD40L, which binds to CD40 on DCs and stimulates the production of co-stimulatory molecules and cytokines by the DCs

Question 20

Give three examples of negative co-stimulatory molecules

Answer 20

→CTLA-4
→PD-1
→LAG-3

Question 21

What do negative co-stimulatory molecules do?

Answer 21

→inhibit the downstream effector processes initiated by TCR MHC/peptide interaction

Question 22

Which cells are negative co-stimulatory molecules expressed on?

Answer 22

→naïve Tcells

Question 23

What types of cells are PD-1 molecules mostly expressed on?

Answer 23

→Tcells in peripheral tissues
→Bcells
→myeloid cells
→inducible

Question 24

What does CTLA-4 on Tcells bind to?

Answer 24

→CD86(B7-1) on APC

→prevents activation of Bcells

Question 25

When is CTLA-4 epxressed?

Answer 25

→2-3 days post stimulation

Question 26

What does CTLA-4 have a high affinity for?

Answer 26

→high affinity/avidity for CD80

Question 27

What effect does CTLA-4 have on CD28?

Answer 27

→opposing effects because it binds laterally

Question 28

What does CD28 bind to and what is the effect?

Answer 28

→CD80/86 | →co-stimulation

Question 29

On which cells is CTLA4 mostly expressed on?

Answer 29

→T cells in secondary lymphoid organs

Question 30

Compare CTLA4 and CD28

Answer 30

→CTLA4 peak levels of expression lower than CD28 but avidity of interaction is much higher

Question 31

What is ICOS?

Answer 31

→costimulatory molecule expressed mainly on activated CD4+ T-cells following activation

Question 32

What are the cytokines released by APCs for naive Tcell activation?

Answer 32

→IL-6 →IL-12 →TGF-beta →IL-4

Question 33

What are the outcomes of cytokines secreted by APCs for activation?

Answer 33

→activation →survival →differentiation →Tcell polarisation

Question 34

What can cytokines drive Tcells to differentiate into?

Answer 34

→Th1 | →Th2

Question 35

What cytokines do Th1 cells secrete?

Answer 35

→IFN-gamma →IL4,5,10 →cell mediated immunity

Question 36

Which cytokine helps differentiation into Tregs and what is the transcription factor it has?

Answer 36

→TGF-beta →FoxP3

Question 37

Which cytokines help differentiation into Tfh cells and what is the transcription factor it has?

Answer 37

→IL-6 →Bcl6

Question 38

Which cytokines help differentiation into Th17 cells and what is the transcription factor it has?

Answer 38

→Il-2, IFN-gamma →T-bet

Question 39

Which cytokines help differentiation into Th2 cells and what is the transcription factor it has?

Answer 39

→IL-4 →GATA3

Question 40

Which pathogen is TH17 good for?

Answer 40

→bacteria

Question 41

Which pathogen is Th1 good for?

Answer 41

→viral | →intracellular pathogens s

Question 42

Which pathogen isTh2 good for?

Answer 42

→parasites | →allergic responses

Question 43

What type of secretion is IL-2 and IL-12 by Tcells?

Answer 43

→IL-2= autocrine →IL12= paracrine, released by APC

Question 44

What is the effect of IL-2?

Answer 44

→growth, survival and differentiation factor for T cells and Tregs

Question 45

What do Tregs cells in the thymus do with IL-2?

Answer 45

→have high levels of receptors for IL2 so they gather IL2 up blocking proliferation

Question 46

What is the receptor for IL-2?

Answer 46

→CD25

Question 47

Describe the different surface molecules during immune response on Tcells

Answer 47

→naive Tcells=TCR →in lymph node= CD69 →proliferation= CD25, IL-2 receptor →activation of DCs, macrophages, Bcells= CD40L →control of response= CTLA-4

Question 48

What happens post TCR signalling?

Answer 48

→Modify the expression of surface molecules →Upregulate cytokine production →Undergo active rounds of proliferation →Upregulate expression of pro-survival genes →Upregulate expression of IL-2 and IL-2R-a →Differentiate into effector or memory cells

Question 49

What determines the cytokines produced by APC for Tcell differentiation?

Answer 49

→cellular origin of the APC →maturation and activation status of the APC →Which pathogens or inflammatory mediators were encountered by the APC → tissue environment the encounter takes place

Question 50

What cells do Th1 cells interact with?

Answer 50

→macrophages

Question 51

What is the effect of Th2 cells?

Answer 51

→release cytokines for eosinophils, mast cells, plasma cells

Question 52

What cells do Th17 interact with?

Answer 52

→neutrophils

Question 53

What cells do Tfh cells interact with?

Answer 53

→Bcell via IgM | →results in isotype switching and affinity maturation

Question 54

Which cells do Tregs interact with

Answer 54

→immature dendritic cells | →results in lack of Tcell activation

Question 55

What are the master transcription factors of Th1 cells?

Answer 55

→T-bet, →STAT1 and 4 →IFNgamma can amplify response

Question 56

What are the functions of TH1 cells?

Answer 56

→Induce antibody class switching to IgG (opsonization) →produces IFN-gamma which produces oxygen and nitrogen species →IFNg- Help to activate macrophages to ingest and destroy microbes

Question 57

What cells do not produce IL-4 and as a result does not contribute to TH2 differentiation?

Answer 57

→Dendritic cells →Eosinophils, basophils and mast cells produce IL-4

Question 58

What are the transcription factors of TH2?

Answer 58

→IL-4 activates STAT6 which promotes expression of GATA 3 very important transcription factor

Question 59

What are the functions of TH2 cells?

Answer 59

→eliminate extracellular parasitic infections → Promote class switching to IgE, which causes inflammatory cytokines to be released by eosinophils and mast cells →increase intestinal movement and mucus production →IgE mediates allergy

Question 60

What are the functions of Tfh cells?

Answer 60

→IgE production | →mast cell degranulation