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PA2203- Mod 6 > Bridge bw Innate + Adaptive > Flashcards

Bridge bw Innate + Adaptive Flashcards

1
Q

What are the 3 professional antigen presenting cells

A
  1. Dendridic cells (cDC)
  2. Macrophages
  3. B cells
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2
Q

What are the 2 ways antigens are sampled

A

endocytosis

  1. Phagocytosis
  2. Pinocytosis
  3. receptor mediated endocytosis

Direct fusion

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3
Q

What are the 2 types of antigens (locations they are found)

A

endosomal antigens are called exogenous

cytosolic antigens are called endogenous

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4
Q

How many of each type of MHC does each APC express

A

3-6 MHC1 pros

3-8 MHC2 pros

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5
Q

Where are do MHC1 + 2 cells expressed on predominatly and how many polypeptide chains does each have

A

MHC1- expressed on all nucleated cells ( 1 chain)

MHC2- expressed predominatly on APCs ( 2 chains)

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6
Q

overall pathway of endogenous antigens and exogenous antigens (what are they loaded on and present to)

A

endo- on MHC1 to CD8 t cells (killa)

Exo- on MHC2 to CD4 tcells (helpa)

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7
Q

Where does the start of MHC1 loading happen and what pro holds its structure (and when is it removed)

A

Endoplasmic Reticulum
protein called calnexin helps it maintain its structure and then is subsequently removed when interactin with TAP (transporter associated w peptide processing)

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8
Q

how are foriegn antigens tagged and trimmed down in cytosol

A

foreign antigens are identified and tagged by ubiquitination and fragmented up by proteasome

TAP then transports peptides from cytosol to ER where its further broken down by ERAAP

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9
Q

When the MHC1 complex is loaded what occurs

A

The chaparon protein complex is released and MHCs migrate to the surface of the plasma membrane via the golgi apparatus

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10
Q

Where does the MHC2 complex made and what stabalizes it

A

assemble in the ER and are stabziled by a pro called the invarient chain (li)

Once stabalized can make its way to cell surface via (golgi)

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11
Q

What happens to the MHC2 complex on the way to the cell surface

A
  1. fuses with endosome which degrades invarient chain and leaves CLIP in binding groove
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12
Q

What removes CLIP from the MHC2 complex binding groove on the way to the surface of the cell

A

HLA-DM removes CLIP and allows exogenous antigens in the endosome to bind to peptide groove

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13
Q

How many aa long is antigens that attach to MHC2

A

12-18 aa long

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14
Q

What are the 2 activation signals that APCs need before they are mature

A
  1. proinflammatory cytokines (TnFa + IL6)

2. PAMPs (LPS, DSRNA)

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15
Q

What two things are expressed more in mature APCs

A
  1. increased exprssion of loaded MHC1/2 (better odds for antigen presenting)
  2. Express chemokine receptor CCR7 and co stim molecules
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16
Q

What are the 3 major co sim molecules found on the APC and T cell

A

APC——–tcell

  1. CD80-CD28
  2. CD86-CD28
  3. CD40-CD40L
17
Q

What is the the function of CCR7 and what is it attracted to

A

Produced by mature APCs and are attracted to CL19 and CCL21 in peripheral lympod organs (to the t cells)

18
Q

What are the 3 main signals needed

A
  1. Antigen presentation
  2. Co stim (On APC + T)
  3. Cytokines environment
19
Q

How does signal 1: antigen presentation work + what else binds for it to work

A

Mature APC with MHC loaded with epitope binds with t cell receptor

-T cells coreceptor needs to bind to the MHC as well
(MHC1->CD8, MHC2->Cd4)

20
Q

What confirms that the antigen has minded to the t cell receptor and what relays the signal inside of the cell

A

CD3

ITAMs relay signals downstream activating transcription factors that favour t cell activation

21
Q

What is different of super antigens compared to regular antigens

A

bind to TCR outside of normal groove

-no need for co stem but can cause >20% of t cells released (cytokine storm)

22
Q

Why is co stim: signal 2 needed

A

Necessary step for t cell proliferation, differentiation and survival

-can lead to t cell anergy, t cell deletion or immune tolerance

23
Q

What happens in signal 3: cytokine environment

A

cytokines present during t cell activation help determine differentiation and effector function of the activated t cell

24
Q

What MHC activates CD8 and CD4 t cells

A

MHC1 activate CD8

MHC2 activate CD4

PA2203- Mod 6 (9 decks)

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