Cellular immune response

Question 1

Cellular immune response:

• provided by?
• provides?

Answer 1

• provided by T cells (Th, Tc)

- provides immunity to: intracellular bact, virus, fungi, protozoa, tumors, parasites

Question 2

T cells recognize antigen only when it is

Answer 2

presented on the surface of APC by MHC I molecules

Question 3

T cells must recognize ____ to start immune response

Answer 3

antigens

Question 4

Infected cells are

Answer 4

killed, activated & destroyed intracellular organism/pathogen

Question 5

T cell cytotoxicity, 2 mechanisms?

Answer 5

Intrinsic & extrinsic pathway

Question 6

Intrinsic pathway

Answer 6

• release of enzymes (granzymes & perforins) from cytotoxic T cells
• Granzymes go to mitochondria to produce Cytochrome C
• stimulates caspases which produce DNA fragmentation, cytoskeletal distruption, chromatin disruption
• all leads to APOPTOSIS

Question 7

Extrinsic pathway

Answer 7

• cytotoxic T cells have CD95L binds w/ CD95 on target cells
• Binding forms DISC (Death Inducing Signaling Complex)
• This produces caspase 8
• leads to APOPTOSIS

Question 8

Three different types of caspases

Answer 8

initiator-multi-molecular death complexes
effector-break down cellular structures
inflammatory-activated by multimolecular infammasomes

Question 9

Major morphological features of cell death by apoptosis

Answer 9

• normal cell
• clumping of chormatin, blebbing of cell membrane, loss of organelles
• nuclear fragmentation
• apoptotic bodies

Question 10

Only 1 type of antigen presenting cell that can trigger cellular/humoral response

Answer 10

dendritic cells –> antigens must be endogenous or intracellular. Only presented on MHC I. Produce increase IL-12

Question 11

Only molecule that interacts with MHC I is

Answer 11

CD8

Question 12

CD40/CD154 interaction w/ Dendritic cell. Helper cell –> Th1 w/ CD4. Produce increase IL-2 & IFN-γ. Produce activation of

Answer 12

CD8 T cells. Main activity on target cell –> apoptosis, recognize MHC I & antigen

Question 13

CD4 produces increase in

Answer 13

IL-12 which produces even more activation of dendritic cells. CCL22 is chemotoxic

Question 14

CD8+ T cell mediated cytotoxicity

Answer 14

• CAM- “arms” that hold target cell from cytotoxic T cell
• Fas liknks w/ FasL
• CD8 –> MHC I
• Granules move towards cell interaction
• Cytotoxic T cell release Lytic granuales (LG) and induce apoptosis on target cell

Question 15

When target cell is affected by LG, MHC I

Answer 15

MHC I & CD8 degrade as well

Question 16

Major pathways that cells of the immune system can kill target cells. (target cells are tumor, or infected cells)

Answer 16

• cytotoxic T cell = MCH restriction
• macrophage = not MHC restricted
• Neutrophil = not MHC restricted
• NK cell = not MHC restricted

Question 17

What can be released by Th1 cells that activates macrophages and enables them to kill otherwise resistant intracellular bacteria?

Answer 17

IFN-γ and IL-2

Question 18

____ are very important in activating the macrophage

Answer 18

cytokines

Question 19

Two pathways by which macrophages can be activated

Answer 19

• one involves IFN-γ production but NK cells & is an innate pathway
• one is mediated by IFN-γ from Th1 cells and is an adaptive response

Question 20

Depending on their cytokine, macrophages may be ____ activated or ____ activated

Answer 20

• classically (M1 cells)

- alternatively (M2 cells)

Question 21

What cells have a major regulatory role and are critical to granuloma formation & wound healing? Producing very different cytokine mixtures

Answer 21

M2 cells

Question 22

Classical activation

Answer 22

IFN-γ, TNF-α (Th1 cells) –> M1 –> Increased IL-1, 6, 12, 23, NO, iNos –> INFLAMMATION

Question 23

Alternative activation

Answer 23

IL-4,10,13 (Th2 cells, Treg cells) –> M2 –> increased IL-1RA, IL-10, Arginase, TGF-β –> RESOLUTION OF INFLAMMATION- wound repair, cell proliferation

Question 24

Naive CD8+ T cell differentiates into

Answer 24

• effector CD*+ T cell (killing of infected target cell, macrophage activation)
• memory CD*+ T cell (peripheral tissues)

Question 25

Effector Memory T cell:

Answer 25

• CD44+
• Increase IL-2 receptor
• Increase adhesion molecules
• Increase IL-4, IFN-γ
• Increase TCR stimulation
• IL-15 –> Tc memory survival
• Human T cell memory survival 8-15 years

Question 26

T cell cytotoxicity induces apoptosis on the target cell by the activation of caspase cascade (extrinsic and intrinsic) T/F

Answer 26

TRUE

Question 27

The extrinsic & intrinsic pathways triggers a cascade of enzymes activation to induce apoptosis on the target cell these pathways are activated by the interaction of T cell receptor and the MHC type I antigen. T/F

Answer 27

TRUE