Tolerance and MHC restriction

Question 1

Does the Thymus have Afferent lymph

Answer 1

NNNOOOOO

Question 2

does the Thymus have HEVs

Answer 2

NNOOOOO

Question 3

how does the T cells enter the Thymus

Answer 3

blood stream

Question 4

do the T cells that enter the thymus express anything

Answer 4

no CD4, no CD8, no TCR, very little Fas protein,

Question 5

Where are T cells created

Answer 5

Bone marrow

Question 6

what does a very naive T cell express

Answer 6

lots of Bcl-2

Question 7

what is Bcl-2

Answer 7

protein that protects against apoptosis

Question 8

what do T cells mature into

Answer 8

Double Positive cells (in the thymus)

Question 9

what makes DP cells Double Positive

Answer 9

they contain both CD4 and CD8 molecules

Question 10

what do DP cells express

Answer 10

• lots of Fas protein
  -very little Bcl-2
  (become very vulnerable)

Question 11

What 2 tests do DP cells have to pass to live

Answer 11

1. MHC restriction

2. Tolerance to Self

Question 12

What is the other name for MHC restriction test

Answer 12

Positive Selection

Question 13

where does the MHC restriction test take place

Answer 13

the cortex of the thymus

Question 14

what does the cortical epithelial cells ask the T cells in the MHC restriction test

Answer 14

Do you have receptors that recognize one of the MHC molecules on my surface?

Question 15

what is the correct answer to the MHC restriction test

Answer 15

T cell are supposed to recognize one of the MHC molecules on the cortical epithelial cells

Question 16

What does the cortical epithelial cells of the thymus express

Answer 16

1. endogenous peptides on MHC 1
2. exogenous peptides on MHC II
3. Endogenous peptides on MHC II (cross present)

Question 17

T/F all mature T cells must recognize antigen presented by MHC molecules

Answer 17

true

Question 18

After the MHC restriction test what does the Dp cell turn int

Answer 18

a Signle Positive Cell (SP)

Question 19

what destriguishes a T cell as a SP cell

Answer 19

the T cell has now chosen CD4 or CD8

Question 20

What is the other name for the Tolerance Test

Answer 20

Negative Selection

Question 21

where does the tolerance test take place

Answer 21

In the Thymus in the Medulla

Question 22

What is the job of the Thymic Dendritic Cell in the tolerance test

Answer 22

Display self peptides on MHC molecules (correct answer NO)

Question 23

What is the job of the medullary thymic epithelial cells in the Tolerance Test

Answer 23

• cross present endogenous protein on MHC II

- express thousands of tissue-specific proteins

Question 24

How long does the testing last

Answer 24

2 weeks

Question 25

how many pass the test

Answer 25

2 million (3% out of 60 mil)

Question 26

Since we cant present every protein to T cells how do we combat that

Answer 26

1. Make sure T cells never come in contact with proteins that werent on the test
2. N T reg cells

Question 27

T/F secondary lymphoid tissue tend to express the same antigen set as found in the thymus

Answer 27

True

Question 28

What does N T reg stand for

Answer 28

Natural regulatory T cells

Question 29

What is the job of the N T reg cells

Answer 29

Enter secondary lymphoid tissue and inhibit self reactive T cells

Question 30

T cells are anergized if….

Answer 30

they recognize an antigen but do not get co-stimulated

where B7 and MHC expression in low in the tissue

Question 31

Escaped T cells from the Thymus usually die due to what

Answer 31

AICD (over activated | chronic re-stim)

Question 32

Where does B cell tolerance occur

Answer 32

Bone Marrow (similar to T cells)

Question 33

What is Receptor Editing

Answer 33

B Cells that recognize “self” are given a chance to change

Question 34

Escaped reactive B cells usually die because..

Answer 34

no T cell will help a reactive B cell

Question 35

What if B cells undergoing somatic hypermutation change and recognize self

Answer 35

FDCs in germinal center only display antigens that are opsonized. Self antigens are not usually opsonized