E3: L21

Question 1

Tcells originate in the __ and mature in the __ __

Answer 1

thymus, bone marrow

Question 2

what cells go to the thymus from the bone marrow (not just Tcell)

Answer 2

Lymphoid progenitor cells

Question 3

where do lymphoid progenitor cells become thymocytes

Answer 3

thymus cortex

Question 4

what 2 cells do thymocytes contact within the thymus medulla

Answer 4

dendritic and thymic epithelial cells

Question 5

what are the 4 charesterics of DN (double negative) Thymocytes

Answer 5

1. No CD4 or CD8 expression
2. go through 4 DN stages
3. Proliferate under IL-7
4. TCRs develop to recognize specific epitopes

Question 6

what 2 charesterics must be present of TCRs for them to be fully functionsl

Answer 6

double Pos (DP), express CD4 and CD8

Question 7

cortical epithelial cells screen what type of thymocytes

Answer 7

DP

Question 8

what type of epithelial cell expresses both MHC1 and 2

Answer 8

cortical epithelial cells

Question 9

if DP thymocyte has a strong binding with MHC1 it is ___ committed

Answer 9

CD8+

Question 10

if DP thymocyte has a strong binding with MHC2 it is ___ committed

Answer 10

CD4+

Question 11

if DP thymocyte has a weak interaction

Answer 11

apoptosis

Question 12

positive selection is cells that

Answer 12

recognize either MHC 1 or 2

Question 13

T/F: can DP cells be single positive for either CD4 or CD8?

Answer 13

T

Question 14

in negative selection, the interaction between what 2 things is occuring

Answer 14

self-peptides, MHC interactions

Question 15

what is another name for negative selection

Answer 15

central tolerance

Question 16

1 of what 2 cells must be present MHC molecules for negative selection

Answer 16

mTEC or bone marrow derived APCs

Question 17

only cells that pass positive and negative selection are released as

Answer 17

Naive T Cells

Question 18

Positive selection –>
about recognition of ___ –>
___ mediate, they express __ MHC 1 and MHC 2 –>
__ ___ have the ability to recognize self

Answer 18

MHC, cTEC, both, T cells

Question 19

Negative selection –>
is about ___ of ___ –>
____ and bone marrow derived ___ mediate, __ binding too strong or too weak –>
Self-___ cells are removed

Answer 19

recognition of self, mTECs and APCs,
TCR, self-reactive

Question 20

As the quantity of thymocytes decrease, TCR affinity ___

Answer 20

increases

Question 21

high TCR affinity means

Answer 21

thymocyte doesn’t bind too tight/loose to MHC 1 or MHC 2

Question 22

tolerance is the prevention of an immune response against ___ structures

Answer 22

self

Question 23

___ tolerance - deletion of lymphocytes before they mature

Answer 23

central

Question 24

where does central tolerance occur

Answer 24

primary lymphoid organs

Question 25

in central tolerance, ___ cells are selected and later used to regulate the immune response

Answer 25

Thymic regulatory T cells

Question 26

___tolerance occurs outside bone marrow and thymus (primary lymphoid organs)

Answer 26

peripheral

Question 27

peripheral tolerance occurs vis induction of what cell

Answer 27

pTreg

Question 28

___ selection occurs with the recognition of foreign antigens

Answer 28

clonal

Question 29

__ tolerance is deletion of cells or induction of pTreg cells for those cells which recognize self antigens

Answer 29

peripheral tolerance

Question 30

___ cells negatively reg immune responses

Answer 30

Treg

Question 31

name for antibodies that induce tolerance

Answer 31

tolerogens

Question 32

3 things that can occur when T cells interacting with tolerogens

Answer 32

apoptosis, become anergia, regulated by Treg secretions

Question 33

can tolerogens deplete pro inflammatory cytokines

Answer 33

yes

Question 34

can tolerogens help to shut down allergic responses

Answer 34

yes

Question 35

can tolerogens inhibit APCs

Answer 35

yes

Question 36

can tolerogens secrete inhibitory cytokines

Question 37

when tolerogens bind Ag-MHC 2 via TCR the effect is

Answer 37

down regulated immune response

Question 38

when tolerogens secrete inhibitory cytokines, the effect is

Answer 38

decreased inflammtion

Question 39

The following mechanisms Promote ___

Answer 39

fetal exposure
oral exposre
high antigen doeses
intravenous
low costimulation levels
immature or unactivated APCs
inhibitory cytokines or surface markers