Cytotoxic T cells

Question 1

what does CD8+ T bind to on dendritic cells?

Answer 1

peptides on MHC class I molecules on dendritic cells

• usually on Dendritic cells that take up virus (processed by proteasome) and present on MHC class I

AND
CD28 on T cell binds to costimulatory molecule B7 on DC

binding induces clonal expansion of CD8+ T cells

Question 2

Cytotoxic T lymphocytes or CTLs include … cells which are good at responding to trial infections

Answer 2

CD8+ T cells

Naive CD8+ T cell Differentiates after clonal expansion into CTLs which are also called effector cells

Question 3

what is cross presentation refer to?

Answer 3

Cross presentation refers to when a dendritic cell presents a viral antigen to a T cell

• it is a crucial role of dendritic cells to present virus
• dendritic cell picks up virus and puts a viral peptide on MHC I

Question 4

Clonal expansion of CD8+ T cells is WAY larger than for CD4+ T cells

Question 5

what is the difference between naive CD8+ T cells and CTLs or effector cells?

Answer 5

CTLS have granules impt for killing function of CTL - include perforin and granzymes

Question 6

Naive CD8+ T cells responses to viral infection involve:

Answer 6

1. The cross-presentation of viral antigens by DCs
2. clonal selection and expansion of antigen-specific T cells
3. differentiation into effector cells called cytotoxic T lymphocytes (CTLs), which have cytotoxic granules called perforin and granzymes that help kill

Question 7

naive t cells are initially activated in ..

Answer 7

secondary lymphoid organs

Question 8

this granule perturbs membrane integrity, will insert itself into membrane of epithelial cells and allow entry of granzyme into epithelial

Answer 8

perforin

Question 9

this granule is a proteolytic enzyme that activates caspases then DNAses in the epithelial cell leading to apoptosis of infected cell

Answer 9

granzymes

Question 10

In addition to releasing granules (perforin and granzymes) , CTLs also release … that

Answer 10

inflammatory cytokines - such as interferon gamma

Question 11

when activated native T cells differentiate into CTLs (in lymph nodes) then the activated CTLS:

Answer 11

• mirgrate out of lymph nodes and into infected tissue
• recognize viral peptides displayed on MHC class I molecules on infected cells
• release granzymes and perforin to kill infected cell
• release cytokines to promote inflammation in the infected tissue

Question 12

After an infection is cleared, these lymphocytes are no longer necessary. Effector T and B cells have functions that promote inflammation and tissue damage, which could make them dangerous. After immune clearance of a microbe, the vast majority of the lymphocytes that expanded to clear the microbe undergo apoptosis. This reduction of lymphocyte numbers is known as …

Answer 12

contraction

Question 13

A small number of antigen-specific lymphocytes differentiate into … cells. These can persist for many years and are the mediators of immunologic memory.

Answer 13

Memory cells

Question 14

The first adaptive immune response to a particular type of pathogen is known as the …. immune response. A subsequent response to the same type of pathogen re-activates memory cells and is known as a … immune response.

Answer 14

primary

secondary

Question 15

…. is a new type of therapy that involves using monoclonal antibodies that bind to and block inhibitory receptors (CTLA-4 & PD-1)

Answer 15

checkpoint blockade

Question 16

if you wanted, how would you stop T cell expansion?

Answer 16

by using an inhibitory receptor such as CTLA-4 or PD-1 that have higher affinity than CD28 (normal costimulatory) for DCs and lead to slowing down proliferation/expansion of T cells

Question 17

Using monoclonal antibodies that target CTLA-4 or PD-1, will bind to and block the inhibitory receptors. What is the result?

Answer 17

T cell proliferation - can go and kill tumor or infetion

• one of the therapeis for cancer

Question 18

CTLA-4 blockade occurs in the …. while PD-1 blockade occurs in the …

Answer 18

lymph nodes

tissue (tumor site)

Question 19

CD28 binds to B7 molecules, but ____________ binds to B7 with higher affinity. This binding blocks the interaction of CD28 with B7 that is necessary for costimulatory signaling.

Answer 19

CTLA-4

Question 20

High expression of ____________ by tumor cells could render that tumor resistant to T cell immunity.

Answer 20

PD-L1

PD-1 on T cells can recognize and bind to PD-L1 on tumor cells but becomes exhausted and doesnt work

• PD-1 indicates T cell exhaustion

therapy- monoclonal antibody to block PD-1 so that prevents inhibitory signaling - t cell now reawakened

Question 21

when t cells and b cells gain immune functions (after naive cell) they become … cells

Answer 21

effector cells

naive CD8+ t Cells becmoe Cytotoxic T cells
naive CD4+ T cells become helper T cells
naive B cells become plasma cells

Question 22

when t cells and b cells gain immune functions (after naive cell) they become effector cells
naive CD8+ t Cells becmoe … cells
naive CD4+ T cells become …. cells
naive B cells become ….. cells

Answer 22

naive CD8+ t Cells becmoe Cytotoxic T cells
naive CD4+ T cells become helper T cells
naive B cells become plasma cells

Question 23

B cells coordinate … immunity
Plasma cells make antibodies
function: complement fixation, ADDC, opsonization, neutralization

T cells coordinate … immunity
function: direct killing of infected cells, activation of innate immune cells, activation of B cells

Answer 23

Humoral immunity

cell-mediated adaptive immunity

Question 24

CTLs can target and kill any cell except what?

Answer 24

RBCs

why?
bc RBCs lack nuclei
only cells that are nucleated will express MHC I on surface and therefore can be targeted by CTLs

Question 25

what 2 effector cells are major cellular sources that both secrete IFN- γ in the defense against cellular pathogens?

Answer 25

Th1 and CTLs