Lec 9: Antigen recognition

Question 1

What is an antigen

Answer 1

and antigen is a substance that stimulates an immune response.
They contain intact epitopes that are recognized by BcR
They contain processed peptide epitopes that are recognized by TcR

Question 2

What type of antigens do B cells recognize

Answer 2

intact antigens

Question 3

What type of antigens do T cells recognize?

Answer 3

processed antigens

Question 4

What might hide a liner or conformational epitope from its binding domain?

Answer 4

Either protein is denatured, or the native folding of the protein hides the linear domain

Question 5

Epitope

Answer 5

Ag-Ab interaction

the epitope is the portion of the antigen recognized by the antibody

-> antigenic determinant

Question 6

Paratope

Answer 6

Ag-Ab interaction

the paratope is the portion of the antibody that binds an epitope

-> antigen binding site

Question 7

Multivalent antigen

Answer 7

contains more than one identical epitope

Question 8

Purpose of a multivalent antigen

Answer 8

can incrementally stablize BcR or antibodies bound to FcR on the cell membrane

Multivalent antigens can cluster reeceptors

envelope or capsid proteins on viruses
cell surface proteins
stabilize BcR bound to FcR and cluster them on the cell surface
-> activation and cell signalling

Question 9

Procesed antigen

Answer 9

Antigen bound to MHCII and presented to TcR on a CD4 cell

Question 10

intact antigen

Answer 10

soluable antigen binding to a B cell

Question 11

What is the difference in the way T cells and B cells recognize antigen? **

Answer 11

B cells = intact

T cells = processed

Question 12

What types of antigens does MHC class I recognize

Answer 12

endogenous Ag
(and exogenous antigen cross-presented by CD8+ DCs only)
MHC I peptide\CD8+ cells

Question 13

What types of antigens do CD1d recognize

Answer 13

endogenous and exogenous lipid Ag

NKT cells

Question 14

MHC class II

Answer 14

exogenous and endogenous Ag
MHC II-peptide
CD4+ T cells

Question 15

BcR and antibodies

Answer 15

intact Ag

B cells and cells expressing FcRs

Question 16

Which cells are MHC I expressed on

Answer 16

all nucleated cells

Question 17

Which cells are MHC II expressed on

Answer 17

APCs ie DCs, peptide is not fully in the pocket

Question 18

Which is the only type of cell that can activate a naive T cell

Answer 18

DC

Question 19

name all of the APCs

Answer 19

DC
macrophage
monocyte
B cell
epitheliad cell]
eosinophil

Question 20

Purpose of shutting off cellular proteasome

Answer 20

means that MHCI antigen presentation is stopped

-> inhibition to mask cytocolic antigens

Question 21

CD8+ DCs can cross-present antigen

Answer 21

cross-presentation occurs when exogenous antigens are transferred to the MHCI pathway

Question 22

what the fuck is cross presentation

Answer 22

idk

Question 23

Antigen cross-presentation assists when MHCI pathways are compromised

Answer 23

disruption of the proteasome can disrupt MHCI presentation in APCs
Transfering exogenous antigen to MHCI can overcome this deficiency

Question 24

What is the difference in early TLR responses between DCs and macrophages

Answer 24

DC -> pepides stay on the surface

macrophages -> transient peptides

Question 25

DC-T cell interactions

Answer 25

T cells activate by way of multipe antigen recognition events, and stable synapses only form at specific stages of Ag presentation T cells sampling DC with no antigen in lymph node = short contact T cells sampling DC with antigen in lymph node = long contact -> binds MHC and waits for co-stimulation

Question 26

The Tcr-CD3 complex

Answer 26

only processed antigen will do assessing self vs non-self by peptide sampling mature T cells weakly recognize MHC and only activate if presented with cognate ligans T cells also require co-stimulation to activate

Question 27

Co-stimulaton via cytokines

Answer 27

T cells need cytokine-mediated co-stimulation as a final act | -> secreation of IL-2 = clonal proliferation

Question 28

Co-stimulation of T cells with CD80/CD86 via CD23/CTLA-4 ligand

Answer 28

directs howe a T-cell will proliferate and differentiate

Question 29

DC microenviroment sets the stage for T cell programming

Answer 29

DC microenvironment sets the stage for T cell programming Resting = Low Ag, no costimulation -> short contacts and leads to tolerance Active = high Ag, high costimulation and cytokines -> long contacts and leads to effectors Exhausted DC= high Ag, High costimulation -> short contacts and leads to memory

Question 30

DC instruction of T cells determines

Answer 30

ON or OFF Type of response Population size of Activated T cells

Question 31

Multiple signals drive T cell subtype differentation

Answer 31

signal 1 = MHC: TcR singla 2 = costimulation signal 3 = cytokine and cellular context

Question 32

# Define the follownig: Antigen epitope paratope

Answer 32

?

Question 33

How does the type of epitope impact antibody binding? give an example

Answer 33

?

Question 34

Compare and contrast: MHCI antigen processing pathway MHCII antigen processing pathway Cross-presentation

Answer 34

?

Question 35

What are the 3 signals required for a DC to activate a naive T cell?

Answer 35

?