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Premidterm Term 3 - Immunology > Lecture 21 > Flashcards

Lecture 21 Flashcards

1
Q

When do T cells recognize antigens

A
  • only when presented on specialized molecules

- they must be bound on the MHC of the APC

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2
Q

How do antigen and lymphocytes meet?

A

Secondary lymph tissue

  • spleen ( blood borne antigens)
  • lymph nodes
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3
Q

T-cell antigen presentation by dendritic cells

A

▪ Dendritic cell in epithelium: capture microbial antigen
▪ Activation of dendritic cells
▪ Migration to draining lymph node (chemokines)
▪ Maturation: Due to cytokines and TLR- signaling
▪ Expression of MHCII and co-stimulators for stimulation of T cells

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4
Q

Where would I fund the dendritic cells

A

They can be found in the Paracortex

Which is also where T cells can be found

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5
Q

Give the 3 signals of antigen recognition

A

Signal 1- antigen presentation
Signal 2- co stimulators signal
Signal 3 - cytokine secretion

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6
Q

What are MHC used for

A
  • antigen processing
  • antigen presentation
  • responsible for graft rejection
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7
Q

What are the cluster of genes of the MHC called and break them down

A

HLA (human leukocyte antigen)
MHC class 11 - DP ,DQ,DR
MHC 1 - B,C,A

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8
Q

The alleles in MHC class II

A

DP,DQ,DR

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9
Q

The alleles In MHC I

A

A,B,C

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10
Q

The alleles in MHC III

A
  • complement
  • HSp70
  • TNF
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11
Q

Class I MHC structure

A
  • In the transmembrane you’ll find the alpha Chain which is encoded by A,B,C regions
  • B2 micro-globulin (encoded by another gene in another chromosome )
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12
Q

Class II MHC structure

A

– α1 and α2 chain
• Transmembrane
– β1 and β2 chain
• transmembrane

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13
Q

Difference between where MHC I and MHC II are expressed

A

MHC I are expressed on the majority of nucleated cells

MHC II expressed on antigen presenting cells (APC)(macrophages ,dendritic cells , B cells )

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14
Q

MHC I - PEPTIDE BINDING

A

-▪a3, binds to CD8 on cytotoxic T cells

▪Presents an endogenously processed antigens

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15
Q

MHC II - PEPTIDE BINDING

A

▪ b2, highly conserved, binds to CD4
on helper T cells

Present Ag that are in the phagosome

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16
Q

which is the best professional APC and why

A
  • Dendritic cells

- has antigen presentation to naïve T cells

17
Q

who do macrophages present antigens to

A

-CD4 effector T cells

-

18
Q

who do B lymphocytes present antigens to

A

-CD4 helper T cells

19
Q

how are EXOGENOUS
PATHOGENS
eliminated

A 
Eliminated with the help of:
T helper cells that use antigens
generated by
ENDOCYTIC PROCESSING
Antigens generated by endogenous and endocytic antigen
processing activate different effector functions
ENDOGENOUS
PATHOGENS
EXOGENOUS
PATHOGENS
Antigens presented to TH cells by
MHC Class II
20
Q

how are ENDOGENOUS

PATHOGENS eliminated

A

Killing of infected cells by CTL that
use antigens generated by
CYTOSOLIC PROCESSING

Antigens presented to Tc cells by
MHC Class I

21
Q

describe the cytosolic pathway

A

-ubiquitin-proteins targeted for lysis combine w/ a small protein
-ubiquitin -protein complex is degraded by a proteasome
-specific proteasomes generate peptides which can bind to MHC 1
-Cytoplasmic cellular proteins, including non-self proteins
are degraded continuously by a multi-catalytic protease of 28 subunits
-The components of the proteasome are induced by IFN-y

22
Q 
Transporters associated with
antigen processing (TAP1 & 2)
A
  • put in the ER
  • transported across ER
  • to put antigens in the MHC molecule
23
Q

what do immuno evasins do

A 
• Viruses block MHC class I from properly
presenting them to CD8 T cells.
✓Inhibit peptide transport
✓Inhibit peptide loading
✓Cause MHC class I degradation
24
Q

what does HSV protein do

A

protein blocks transport

of viral peptides into

25
Q

what does the adenoviral protein do

A

protein
retains MHC
class I in the ER

26
Q

will inactive virus raise a response

A

-raises a weak CTL response
-Antigens from inactive viruses are processes via the
exogenous pathway (MHC Class II presentation)

27
Q

Cross-Presentation

A
  • exogenous antigens normally processed by

phagolysosomes (MHC-II) are presented by MHCI (Exception to the MHC Class I rule)

28
Q

Cross -Priming

A
  • then presented to and activate CD8+ T-cell
29
Q

endocytic pathway

A

-Class II MHC a and b bind invariant chain blocking binding of endogenous
-MHC complex is routed through golgi to endocytic pathway compartments
-invariant chain is degraded leaving CLIP fragment
-exogenous antigen is taken up ,degraded routed to endocytic pathway compartments
HLA -DM mediates exchange of CLIP for antigenic peptide
-class II MHC peptide is transported to plasma membrane

Premidterm Term 3 - Immunology (5 decks)

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