Week 9: T Cells Receptors And Mhc

Front 1

T cell receptors able to make any changes after cellular activation:
a. production of secreted receptor
b. isotype switching
c. somatic mutations
d. none, T cells do not undergo changes after cellular activation
d. a, b and c are correct

Back 1

a. receptor is not secreted and remains on the transmembrane throughout the process
b. no isotype switching
c. does not undergo somatic mutation
D IS CORRECT
e. none of a,b,c are correct

Front 2

2. T cell receptors fall under allelic exclusion:
a. True
b. False

Back 2

true - If gene rearrangements are successful, no further
rearrangements occur. This is a process called
allelic exclusion. Alpha and Beta are excluded via allelic exclusion if both gamma ans delta rearrange functionally

Front 3

Differences and similarities between B and T cells

Back 3

Front 4

Why is clonal expansion so important?
a. to select for specific cells
b. to secrete cytokines
c. to kill target cells
d. to increase the numbers of antigen specific cells

Back 4

d. to increase the numbers of antigen specific cells
as there is no change in affinity of TCR in expansion

Front 5

The elimination of self-reactive thymocytes is called ________.
a. positive selection
b. negative selection
c. tolerance
d. clonal selection

Back 5

b. negative selection

positive selection is where thymocytes are selected if they are affinity with MHC, tolerance is not a thing - or otherwise a thymocyte which passes negative selection and clonal selection describes the overall process of VJD rearrangement and negative selection and survival through functional rearrangement and not falling to apoptosis.

Front 6

5. Which type of T cell is most effective against viruses?

a. Th1
b. Th2
c. cytotoxic T cells
d. regulatory T cells

Back 6

c. cytotoxic T cells*

Front 7

6. What portion of the alpha beta T cell receptor determines antigen specificity:

a. V region of alpha and beta chains
b. the constant region
c. CD3
d. the J region

Back 7

a. V region of alpha and beta chains

Front 8

7. What are the 2 types of T cell receptors:

Back 8

CD4+
CD8+

Front 9

8.what are the 3 kinds of molecules encoded by MHC:

Back 9

class I, class II, class III

Front 10

9.what are the 4 regions of the alpha/beta T cell receptor

Back 10

alpha constant, alpha variable
beta constant, beta variable

Front 11

10. What are the regions on an human MHC (HLA) Class I locus:

Back 11

alpha 1
alpha 2
alpha 3
tm
c
c

Front 12

11.What are the regions on an human MHC (HLA)class II locus

Back 12

Front 13

12. What are the required signaling molecules for T cell receptors:

Back 13

**

Front 14

13.On each T cell what complex are all T cell receptors associated with:
a. CD3
b. CD4
c. CD8
d. RAG1/RAG2

Back 14

a. CD3

Front 15

14. What is CD 4 associated with:
a. CD3
b. MHC class II
c. Rag1/Rag2
d. MHC class I

Back 15

b. MHC class II

Front 16

15.what is commonly called the invariant chains of T cell receptor complex:

Back 16

(TCR-α) chain

Front 17

17.What is the role of the CD3 complex:
a. CD3 necessary for cell surface expression of T cell receptors
b. Forms a corboxyl portion of the secreted TCR
c. transduces signal after antigen interaction with T cell receptors
d. Both a and b are correct
e. Both a and c are correct

Back 17

**

Front 18

18.What is the specificity of a T cell receptor:
a. Binds to many different epitopes
b. Is specific for one epitope
c. Binds specifically with one conformational protein antigens
d. none of the above are true.

Back 18

**

Front 19

19.What is the structure of the alpha/beta T cell receptor:

Back 19

**

Front 20

20.what must a peptide do to induce a T immune response:

Back 20

**

Front 21

21.What recognises antigen presented in MHC:
a. Antibodies
b. B cell receptor complex
e. Toll-like receptors
d. T cell receptors

Back 21

**

Front 22

22.where are alpha beta T cell receptors found:

Back 22

**

Front 23

23.where are gamma delta T cell receptors found:

Back 23

**

Front 24

24. ______ is a heterodimer composed of either αand βchains or γand δchains.
a. MHC
b. BCR
c. TCR
d. immunoglobulin

Back 24

**

Front 25

25. CD8 and CD4 are classified as ______ based on their abilities to recognize the MHC-Ag
complex and their roles in signal transduction.
a. Co-receptors
b. peptide binding sites
c. immunoglobulins
d. antigens

Back 25

**

Front 26

26. How many variable domains does the TCR molecule have and what are they similar
to?

Back 26

**

Front 27

27. TCR is associated on membrane with a multi-component signal-transducing complex
called _____.
a. MHC
b. CD3
c. alpha-domain
d. Beta sheet

Back 27

**

Front 28

Define antigenic determinant

Back 28

antigenic determinant:(also, epitope) one of the chemical groups recognized by a single
type of lymphocyte antigen receptor

Front 29

Define antigen presentation

Back 29

antigen presentation:binding of processed antigen to the protein-binding cleft of a major
histocompatibility complex molecule

Front 30

Define antigen processing

Back 30

antigen processing:internalization and digestion of antigen in an antigen-presenting cel

Front 31

Define antigen receptor

Back 31

two-chain receptor by which lymphocytes recognize antigen

Front 32

Define clone

Back 32

clone:group of lymphocytes sharing the same antigen receptor

Front 33

define clonal expansion

Back 33

clonal expansion:growth of a clone of selected lymphocytes

Front 34

Define clonal selection

Back 34

clonal selection:stimulating growth of lymphocytes that have specific receptors

Front 35

Define constant region domain

Back 35

constant region domain:part of a lymphocyte antigen receptor that does not vary much
between different receptor types

Front 36

Define cytotoxic t cells

Back 36

cytotoxic T cells (Tc):T lymphocytes with the ability to induce apoptosis in target cells

Front 37

Define effector T cells

Back 37

effector T cells:immune cells with a direct, adverse effect on a pathogen

Front 38

Define helper T cells

Back 38

helper T cells (Th):T cells that secrete cytokines to enhance other immune responses,
involved in activation of both B and T cell lymphocytes

Front 39

Define immunological memory

Back 39

immunological memory:ability of the adaptive immune response to mount a stronger and
faster immune response upon re-exposure to a pathogen

Front 40

MHC d.

Back 40

major histocompatibility complex (MHC):gene cluster whose proteins present antigens to
T cells

Front 41

Memory T cells

Back 41

memory T cells:long-lived immune cell reserved for future exposure to an pathogen

Front 42

MHC class I

Back 42

MHC class I:found on most cells of the body, it binds to the CD8 molecule on T cells

Front 43

MHC class II

Back 43

MHC class II:found on macrophages, dendritic cells, and B cells, it binds to CD4 molecules on T cells

Front 44

negative selection

Back 44

negative selection:selection against thymocytes in the thymus that react with self-antigen

Front 45

polyclonal response

Back 45

polyclonal response: response by multiple clones to a complex antigen with many determinants

Front 46

primary adaptive response

Back 46

primary adaptive response:immune system’s response to the first exposure to a pathogen

Front 47

positive selection

Back 47

positive selection:selection of thymocytes within the thymus that interact with self, but not
non-self, MHC molecules

Front 48

Regulatory T cells

Back 48

regulatory T cells (Treg):(also, suppressor T cells) class of CD4 T cells that regulates other
T cell responses

Front 49

secondary adaptive response

Back 49

secondary adaptive response:immune response observed upon re-exposure to a pathogen,
which is stronger and faster than a primary respons

Front 50

T cell tolerance

Back 50

T cell tolerance:process during T cell differentiation where most T cells that recognize
antigens from one’s own body are destroyed

Front 51

TH1 cells

Back 51

Th1 cells:cells that secrete cytokines that enhance the activity of macrophages and other
cells

Front 52

TH2 cells

Back 52

Th2 cells:cells that secrete cytokines that induce B cells to differentiate into antibody-secreting plasma cells

Front 53

Variable region domain

Back 53

variable region domain:part of a lymphocyte antigen receptor that varies considerably
between different receptor types

Front 54

Describe the overall structure of a T cell receptor

Back 54

A TCR has two polypeptides which span the cell membrane which contain like BCRs constant and variable regions. TCRs have disulfide links between the polypeptides and within variable and contant regions. Both peptides form Ag binding site

Front 55

What are the two classes of T cell receptor?

Back 55

1. alpha beta
2. gamma delta

Front 56

What are the regions of a T cell receptor?

Back 56

Antigen binding site, alpha chain, beta chain, variable region, constant region, transmembrane region and cytoplasmic tail.

Front 57

Describe how TCR repertoire is generated

Back 57

1. VDJ genes
2. N region diversification

Front 58

What is N region diversification

Back 58

where nucleotides are inserted by the enzyme:
deoxynucleotidyl-transferase.

Front 59

Compare VDJ of TCR with BCR VDJ

Back 59

- TCR more complicated
- alpha and gamma use V and J segments
- beta and delta use VD and J segments

Front 60

Which has the most genes coding for TCR

Back 60

There are more variable alpha and beta genes than delta and gamma. There are 50-100 alpha/beta and about 5-10 delta/gamma.

Front 61

Which genes are located on the same locus? what does this mean?

Back 61

delta VDJ are located within alphas V and J segments on the same locus. Any productive manipulation of the alpha chain would exclude delta so for this reason, a T cell cannot be both an alpha and a delta.

Front 62

What coordinates the recombination of TCR?

Back 62

recombinase activating genes RAG-1 and RAG-2 bind to RSS like in immunoglobulin recombination. RAG-1/2 recognise heptamers and nonamers followed by spacing with the 12/23 rule.

Front 63

What happens if the RAG gene is impaired or missing?

Back 63

homologous recombination events are abolished, giving rise to severe combined immunodeficiency (SCID).

Front 64

Describe components of recombination and their funcitons

Back 64

Front 65

What is a functional V region on the alpha chain?

Back 65

V and J

Front 66

Explain the process of creating a TCR

Back 66

alpha chain = V + J
- then transcription and splicing with C region generates mRNA that is transplated for alpha protein
beta chain = V + J + D
- tx and splicing with C region generates mRNA that is translated to create beta protein
- a and b pair after synthesis to yield TCR heterodimer

Front 67

Define allelic exclusion

Back 67

two alleles --> m and d
only need one, once one rearranges, the other one doesn't need to and is deleted.
No more rearrangment, the other one won't switch on.
Othe chromosome is not switched on. 2 chances

Front 68

Describe diversity of TCR

Back 68

More beta and alpha segments --> different combinations. Total diversity increased than Ab.

Front 69

What is required to reconise an Ag on TCR

Back 69

alpha and beta form a pocket and both determine the region for Ag, so connection on both chains.

Front 70

biggewst diference between BCR and TCR

Back 70

no somatic hypermutation. Only one rearrangement. No point mutations - no increased affinitiy after Ag contact or during expansion

Front 71

Generation of TCR diversity

Back 71

rand

Front 72

What is the issue with the TCR

Back 72

receptor will bind but it will not signal
- CD3 are coreceptor
- needed for signalling

Front 73

What is ITAM

Back 73

immunoreceptor tyrosine based activation motif, this is a common mitf seen in the cytoplasmic region

Front 74

Describe the structure of a CD3 complex

Back 74

- 4 chains
- Contains 4 chains [(γ, δ, and ε chains) plus ζ (zeta) or η (eta) or θ (theta)] That forms 3 dimers
- combines via electric charge -TCR has a positive transmembrane region, whereas all chains in CD3 complex are negative and thus attracted to it.

Front 75

What are the chains that can be the fourth chain in the CD3

Back 75

eta, zeta or theta

Front 76

What are examples of accessory molecules on T cells and what do they do? How do they differ from TCR?

Back 76

- CD2, LFA-1, CD28, CD45R
- Bind APC/target cells (via surface molecules)
- Increase strength of adhesion between APC or target cells
- communicate/transduce signals to interior of T cells
- same on all individuals of the same species
- useful as cell markers

Front 77

Describe the stages of T cell and T cell rearrangement

Back 77

Pro T: TCR gamma
Early thymocyte: Tx of Tcry, rearrangement of Tcrbeta
Thymocyte: Tcr alpha, surface expression, CD4 & CD8
Mature: single positive
T cell: helper/cytotoxic

Front 78

How to T cells move through the thymus - what occurs

Back 78

Front 79

Cytotoxic T cells

Back 79

MCH class I
only respond to MHC
destory infected cells
makes some memory
- memory cells are clones only, clonal only, sit in tissue - doesn't need random rearragment. years ++

Front 80

Describe the helper T cell subsets

Back 80

Th1
Th2
Th17
Treg

Front 81

Which Cd4+ cell regulates helminths

Back 81

Front 82

Which CD4+ cell regulates intracellular pathogens?

Back 82

Th1

Front 83

What activates Th1

Back 83

IL12

Front 84

What activates Th2

Back 84

IL4

Front 85

Describe the functions Cd4 cells in adaptive immunity

Back 85

1. cytokines for macrophages
2. b cell activation and Ab production
3. prime CD8
4. kills cells directly