Lymphocytes and their Receptors

Question 1

What types of lymphocytes are there? Of which are involved in the innate immune response?

Answer 1

T lymphocytes, B lymphocytes, and NK cells, which are the only ones involved in the innate response

Question 2

What lymphocyte is associated with the cell-mediated immune response of the adaptive immune response?

Answer 2

T lymphocytes

Question 3

What lymphocyte is associated with the humoral response of the adaptive immune response?

Answer 3

B lymphocytes

Question 4

What cells are formed from a Pre-T cell?

Answer 4

T cells and NK cells

Question 5

What is the difference between a memory cell and a plasma cell?

Answer 5

Memory cells = provide anamnestic response to secondary infections/ antigen reexposure

Plasma cells = terminally differentiated B cells that produce only a specific type of immunoglobulin

Question 6

Where do Pre-T cells migrate, starting during fetal development?

Answer 6

The thymus

Question 7

What cells are the precursors to thymocytes?

Answer 7

Pre-T cells

Question 8

While thymocytes that produce a ______ chain become alpha-beta T cells, those thymocytes that produce what chain become gamma-delta T cells?

Answer 8

Alpha-beta T cells = Beta chain produced

Gamma-delta T cells = Gamma or delta chain produced

Question 9

True or False: Complementarity between the antigen and the TCR dictates the specificity of a response.

Answer 9

True

Question 10

Diversity of TCR components occurs in the ______, as a result of the random rearrangement of germline ____ _________.

Answer 10

Thymus

Gene segments

Question 11

In TCR production, what chain is formed first - alpha or beta? Can it be expressed prior to the other chain’s completion

Answer 11

Beta chain, and no. It must wait until completion of the alpha chain for expression on the T cell surface

Question 12

The V, D, J, and C regions of genetic material along a chromosome are not __________, meaning they are together in a uniform pattern.

Answer 12

Contiguous

Question 13

What genes are transcribed and translated to form enzymes responsible for the reassortment of the V, D, J, and C gene segments in thymocytes?

Answer 13

RAG genes, or recombination activating genes

Question 14

Explain how the beta chain is formed.

Answer 14

Random joining of the D-beta and J-beta gene segments via RAG proteins, that also bring in a V-beta segment to be joined with it as well.

Question 15

Explain how the alpha chain is formed.

Answer 15

Joining of the V-alpha and J-alpha gene segments via RAG proteins, that is also joined with a C-alpha region segment

Question 16

True or False: With the attachment of the C-alpha gene segment with the VJ-alpha segment, is the alpha chain variable region complete.

Answer 16

False, the variable region of the alpha chain is complete following the joining of V-alpha and J-alpha

Question 17

Are RAGs associated with NK cell receptor production?

Answer 17

No, they’re not

Question 18

While RAG proteins can cleave genetic material to form complete segments for alpha and beta chains, what enzyme is associated with excise the intervening DNA to increase the diversity of TCRs?

Answer 18

DNA-dependent protein kinase

Question 19

What step takes place first, within the selection process of thymocytes in the thymus?

Answer 19

Positive selection

Question 20

What is involved with positive selection?

Answer 20

Thymocytes are tested to see if their TCR’s can bind to MHC I or MHC II molecules on thymic APC’s

Question 21

Where in the thymus does positive selection occur?

Answer 21

Cortex

Question 22

What happens if a TCR fails to recognize and bind to a MHC I or MHC II molecules on thymic APC’s, due to a failure to produce a TCR or that its TCR is defective?

Answer 22

It is sentenced to death, via apoptosis

Question 23

Following positive selection where to surviving thymocytes get tested on during negative selection?

Answer 23

Their ability to recognize MHC:antigen complexes

Question 24

What causes a thymocyte to survive the negative selection process?

Answer 24

High affinity binding to Self peptide:MHC complexes and Antigen:MHC complexes

Question 25

While alpha-beta T cells are MHC ________, gamma-delta T cells are MHC ___________.

Answer 25

``` Alpha-Beta = MHC dependent Gamma-Delta = MHC independent ```

Question 26

Why are early thymocytes considered double negative?

Answer 26

They have neither a CD4 or CD8 coreceptor

Question 27

When thymocytes do possess both CD4 and CD8 coreceptors, they are considered -?

Answer 27

Double positive

Question 28

When a mature thymocytes has either a CD4 or CD8 coreceptor only, they are considered -?

Answer 28

Single positive

Question 29

What occurs to thymocytes during positive selection, besides the binding of their TCRs to MHC molecules?

Answer 29

Their commitment to CD4 or CD8 lineages, based on their individual affinity to either MHC I or MHC II molecules (which they have to bind to to pass positive selection)

Question 30

What happens to thymocytes to go from double positive to single positive?

Answer 30

It will turn or switch off the gene that is associated with the CD protein that is not associated with the MHC molecule that they have an affinity for

Question 31

Following passage of both positive and negative selection, as well as commitment to be a CD4 or CD8 thymocyte, what will happen?

Answer 31

CD8+ thymocytes become cytotoxic thymocytes; whereas, CD4+ thymocytes become either helper thymocytes or regulatory thymocytes

Question 32

What causes proliferation and differentiation of helper thymocytes to become Th1, Th2, or Th17 cells?

Answer 32

Antigen presentation

Question 33

What gene allows for thymic epithelial cells to express many of the proteins usually found in other tissues of the body, which prevents the continuance of thymocytes that can react to self cells (which would be eliminated during negative selection)?

Answer 33

AIRE gene or Autoimmune Regulator gene

Question 34

While B lymphocytes develop in either the _____ ______ or _________ _____, this process involves three stages - ________, _________ and ____________.

Answer 34

Bone Marrow or Cloacal Bursa | Maturation, Activation and Differentiation

Question 35

These three sources - ___ ___, ______ _____, and _____ ______ - serve as areas for B lymphocyte __________, which is the generation of mature immunocompetent B lymphocytes as a result of differentiation from ________ precursor cells.

Answer 35

Yolk sac, fetal liver, and bone marrow Maturation Lymphoid

Question 36

What must be present for Pro-B cells to mature into B lymphocyte precursor cells?

Answer 36

IL-7 and bone marrow stromal cells

Question 37

Where is IL-7 produced?

Answer 37

In the bone marrow, and also by thymic stromal cells in the thymus

Question 38

What effect does IL-7 have on IL-2 and its receptors?

Answer 38

It increases both the production of IL-2 and its receptors

Question 39

True or False: The constant region is identical in all antibodies of the same isotype, but differs in antibodies of different isotypes.

Answer 39

True

Question 40

What is the gene arrangement in maturing B cell receptors?

Answer 40

Germline to Dh to Jh, Vh to DhJh, and finally VhDhJh

Question 41

What allows for only the expression of VLJL, kappa or lambda?

Answer 41

Allelic exclusion, where one alleles is expressed and the other is silenced

Question 42

What causes a Pre-B cell to become an immature B cell?

Answer 42

Rearrangement of both the V, D, and J gene regions for the Heavy chains, and the V and J gene regions of the Light chains

Question 43

The combination or grouping of both Ig-alpha/Ig-beta and IgM, forms a -?

Answer 43

B Lymphocyte Cell Receptor Complex (BCR)

Question 44

Are BCRs of immature B cells functional? What happens if they happen to be stimulated?

Answer 44

No they are not, and if they are, they are eliminated or become unresponsive

Question 45

What Ig's are present on fully mature B lymphocytes?

Answer 45

IgM and IgD

Question 46

A change in RNA coding of both heavy chains mu and delta, leads to -?

Answer 46

IgM and IgD expression, respectively

Question 47

What is clonal deletion, and how does it apply to B cells?

Answer 47

Similar to negative selection, those B cells that have a high affinity for self antigens are eliminated

Question 48

Mature B cells leave the bone marrow undergo activation and differentiation in the _________ to become plasma cells.

Answer 48

Periphery

Question 49

B cell receptors have 2 identical ______ and 2 identical _______ chains. The _____ chains are bound to H chains by _______ bonds.

Answer 49

Heavy Light Light

Question 50

Within the BCR complex, what portion serves as the signalling molecule?

Answer 50

Ig-alpha/ Ig-beta

Question 51

What terminal end of the H chain is highly variable and associated with the distal portions of the chain?

Answer 51

N-terminal

Question 52

What is the significance of the C-terminal end of the heavy chain in the BCR?

Answer 52

While expanding the cell membrane, it is identical for each BCR of that isotype

Question 53

Which end of the light chain is more variable? A) C-terminal B) N-terminal

Answer 53

B) N-terminal