CSIM 1.26 - Role of T-cells

Question 1

Where are koplik spots found and what are they indicative of diagnosing?

Answer 1

Found on the buccal mucosa

Measles

Question 2

What is the function of CD8 T-cytotoxic cells?

Answer 2

Killing virally infected cells

Question 3

Which cell type is capable of directly activating CD8 T-cytotoxic cells?

Answer 3

Dendritic cells

Question 4

How are CD8 T-cytotoxic cells activated by APCs other than dendritic cells?

Answer 4

CD4 T-helper cell help (APC activated by CD4 T-cell via Ag specific and MHC recognition)
Activated APC now expresses CD40 and 4-IBL which can co-stimulate naive CD8 T-cytotoxic cells

Question 5

How do CD8 T-cytotoxic cells anchor themselves onto target cells?

Answer 5

Non-specific adhesion molecules:-

LFA-1 on T-cell + ICAM on target cell

Question 6

Define ‘immunological synapse’?

Answer 6

Area of contact between T-cell and target cell

Question 7

What forms the peripheral component of the immunological synapse?

Answer 7

pSMAC = LFA-1 and ICAM adhesion molecules

Question 8

What forms the peripheral component of the immunological synapse?

Answer 8

cSMAC = T-cell receptor (CD4//CD8) + CD28//CD80//CD86 + MHC molecule

Question 9

Which three chemicals are contained within the cytotoxic granules released by CD8 T-cytotoxic cells?

Answer 9

Granulysin
Granzymes
Perforin
(ALL non-specific)

Question 10

How can CD8 T-cytotoxic cells block viral replication and how might this be advantageous?

Answer 10

Release of cytokine IFN-Y

Leads to viral death without cell death

Question 11

Which cytokines are secreted by CD8 T-cytotoxic cells?

Answer 11

IFN-Y - blocks viral replication
TNF-B - activates macrophages
TNF-a - activates and induces N.O

Question 12

Which environmental cytokines facilitate the differentiation of CD4 Th0 cells into T-reg cells and which cytokines are released?

Answer 12

Environmental cytokine = TGF-B

Cytokines released = TGF-B + IL-10

Question 13

Which environmental cytokines facilitate the differentiation of CD4 Th0 cells into T-FH cells and which cytokines are released?

Answer 13

Environmental cytokine = IL-6

Cytokines released = IL-21 + ICOS

Question 14

Which environmental cytokines facilitate the differentiation of CD4 Th0 cells into Th17 cells and which cytokines are released?

Answer 14

Environmental cytokines = TGF-B + IL-6

Cytokines released = IL-17 + IL-6

Question 15

Which environmental cytokines facilitate the differentiation of CD4 Th0 cells into Th2 cells and which cytokines are released?

Answer 15

Environmental cytokines = IL-4

Cytokines released = IL-4 + IL-5

Question 16

Which environmental cytokines facilitate the differentiation of CD4 Th0 cells into Th1 cells and which cytokines are released?

Answer 16

Environmental cytokines = IL-12 + IFN-Y

Cytokines released = IL-2 +IFN-Y

Question 17

What are the functions of Th17 cells?

Answer 17

Attract neutrophils and maintain mucosal integrity

Question 18

What are the functions of Th2 cells?

Answer 18

Help B-cell Ig class switching (humoral immunity)

Question 19

What are the functions of Th1 cells?

Answer 19

Activate macrophages (cell-mediated immunity)

Question 20

How do NK-cells recognise and directly kill virally infected cells?

Answer 20

NK-cells have NO specific Ag receptors however express FCY-RCIII receptors which recognises IgG.1 and IgG.3 antibodies bound to virally infected cells and initiate similar mechanisms as CD8 T-cytotoxic cells

Question 21

Why might having a complete IFN-Y receptor deficiency be particularly damaging?

Answer 21

IFN-Y mediated immunity critical for differentiating Th1 cells and therefore activating macrophages
IFN-Y secreted by CD8 T-cytotoxic cells to block viral replication