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GM Immunology > Ch. 9 Tolerance And MHC Restriction > Flashcards

Ch. 9 Tolerance And MHC Restriction Flashcards

1
Q

Does the thymus express CD4, CD8 or TCR

A

Nope

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2
Q

Does the thymus contain HEV’s or afferent lymphatics

A

Nope

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3
Q

How do T cells enter the thymus

A

The blood

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4
Q

T cell express lots of what that is a protein that protects against apoptosis

A

Lots of Bcl-2

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5
Q

Where do T cells mature

A

Into double positive (DP) cells in the thymus

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6
Q

What type of co-receptor molecules do DP cells contain

A

Both CD4 and CD8

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7
Q

What are DP cells very vulnerable to?

A

Death

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8
Q

What two tests must a DP cell pass to live

A

1) MHC restriction

2) Tolerance to self

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9
Q

What do DP cells express a lot of and very little of

A

Lots of Fas protein on the surface, little Bcl-2

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10
Q

What type of selection is MHC restriction

A

Positive selection

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11
Q

What is positive selection for MHC restriction

A

Maturing T cell must recognize peptides presented on self MHC’s, this takes place in the cortex

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12
Q

What type of selection is tolerance to self in DP testing

A

Negative selection

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13
Q

What is negative selection in the tolerance to self DP test

A

Maturing T cell must not recognize peptides presented on self MHC’s, takes place in medulla

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14
Q

What do cortical epithelial cells ask t cells

A

They see if they have receptors that recognize on of the MHC molecules on the surface. If not then the cell dies

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15
Q

What do cortical epithelial cells do

A

Display peptides MHC 1 molecules made in cell, MHC2 molecules made in cell and sampled from the area

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16
Q

What happens if mature T cells don’t recognize MHC antigen presented molecules

A

They are eliminated

17
Q

After positive selection T cells choose what

A

Either CD4 or CD8 becoming a single positive cell or SP cell

18
Q

What cells give the tolerance to self or negative selection test?

A

Thymic dendritic cells, medullary thymic epithelial cells

19
Q

What do thymic dendritic cells do

A

Display self peptides on MHC molecules, if unrecognizable the death to the T cell

20
Q

What 2 features make the medullary thymic epithelial cells good at testing self tolerance

A

They break MHC peptide expression rules (displaying endogenous AG on MHC 2, like cortical cells) and express several thousand tissue specific proteins

21
Q

Medullary thymic epithelial cells make sure we what

A

Create T cells that don’t recognize our tissue specific proteins that thymic dendritic cells missed

22
Q

What happens when t cells do recognize MHC peptide complexes

A

This is a positive selection, presented on cortical thymic epithelial cells

23
Q

What happens when t cells do not recognize self antigens on MHC

A

This is negative selection, presented on thymic dendritic cells and medullary thymic epithelial cells

24
Q

Naive t cells primarily traffic though where

A

Secondary lymphoid tissues (express same antigen found in thymus)

25
Q

What are natural regulatory t cells from the thymus called

A

nTregs

26
Q

What do nTregs do

A

Control cells that react against self by inhibiting self reactive t cells

27
Q

What do iTreg cells do

A

Prevent over active immune response

28
Q

T cells require what 2 things in peripheral tolerance

A

Enough antigen to cluster receptors and co-stimulatory signals

29
Q

What are anergized t cells

A

T cells that recognize antigen but do not get co-stimulation

30
Q

When dos a t cell usually become anergized

A

In peripheral tissue where B7 and MHC expression is low

31
Q

What is activation induced cell death

A

Naive t cell escapes deletion in thymus, enters into peripheral tissue, gets activated over and over because there is a lot of antigen thus AICD occurs and death from chronic restimulation

32
Q

What is B cell tolerance

A

Similar to thymic tolerance induction for t cells but happens in bone marrow

33
Q

What is receptor editing

A

B cells that recognize “self” and given a chance to change

34
Q

Where and why are B cells restricted from traveling

A

Restricted to traveling from bone marrow to secondary lymphoid organ preventing exposure to “self” antigens or prevent getting anergized or deleted because no T cell help

35
Q

What if b cells undergoing somatic hypermutation change and recognize self

A

B cells in germinal centers usually helped by FDC’s presenting antigen (usually only display opsonized antigens)

GM Immunology (6 decks)

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