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Immunology > Lec 9: Antigen recognition > Flashcards

Lec 9: Antigen recognition Flashcards

1
Q

What is an antigen

A

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

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2
Q

What type of antigens do B cells recognize

A

intact antigens

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3
Q

What type of antigens do T cells recognize?

A

processed antigens

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4
Q

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

A

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

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5
Q

Epitope

A

Ag-Ab interaction

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

-> antigenic determinant

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6
Q

Paratope

A

Ag-Ab interaction

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

-> antigen binding site

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7
Q

Multivalent antigen

A

contains more than one identical epitope

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8
Q

Purpose of a multivalent antigen

A

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

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9
Q

Procesed antigen

A

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

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10
Q

intact antigen

A

soluable antigen binding to a B cell

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11
Q

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

A

B cells = intact

T cells = processed

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12
Q

What types of antigens does MHC class I recognize

A

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

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13
Q

What types of antigens do CD1d recognize

A

endogenous and exogenous lipid Ag

NKT cells

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14
Q

MHC class II

A

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

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15
Q

BcR and antibodies

A

intact Ag

B cells and cells expressing FcRs

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16
Q

Which cells are MHC I expressed on

A

all nucleated cells

17
Q

Which cells are MHC II expressed on

A

APCs ie DCs, peptide is not fully in the pocket

18
Q

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

A

DC

19
Q

name all of the APCs

A 
DC
macrophage
monocyte
B cell
epitheliad cell]
eosinophil
20
Q

Purpose of shutting off cellular proteasome

A

means that MHCI antigen presentation is stopped

-> inhibition to mask cytocolic antigens

21
Q

CD8+ DCs can cross-present antigen

A

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

22
Q

what the fuck is cross presentation

A

idk

23
Q

Antigen cross-presentation assists when MHCI pathways are compromised

A

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

24
Q

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

A

DC -> pepides stay on the surface

macrophages -> transient peptides

25
Q

DC-T cell interactions

A

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

26
Q

The Tcr-CD3 complex

A

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

27
Q

Co-stimulaton via cytokines

A

T cells need cytokine-mediated co-stimulation as a final act

-> secreation of IL-2 = clonal proliferation

28
Q

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

A

directs howe a T-cell will proliferate and differentiate

29
Q

DC microenviroment sets the stage for T cell programming

A

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

30
Q

DC instruction of T cells determines

A

ON or OFF

Type of response

Population size of Activated T cells

31
Q

Multiple signals drive T cell subtype differentation

A

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

32
Q

Define the follownig:

Antigen
epitope
paratope

A

?

33
Q

How does the type of epitope impact antibody binding?

give an example

A

?

34
Q

Compare and contrast:

MHCI antigen processing pathway
MHCII antigen processing pathway
Cross-presentation

A

?

35
Q

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

A

?

Immunology (23 decks)

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