Adaptive Antigen Recognition

Question 1

BCRs are composed of a surface immunoglobulin and two invariant chains, ______ and ______. These ensure surface expression of immunoglobulin and also function in signal transduction.

Answer 1

Ig-alpha

Ig-beta

Question 2

The TCR complex consists of an alpha/beta heterodimer associated with ______ complex proteins. These proteins ensure the cell surface expression of the TCR and is involved in signal transduction.

Answer 2

CD3

Question 3

This is the term for gene rearrangement events that occur in the absence of antigen.

Answer 3

Clonal selection

Question 4

What are the major mechanisms for generation of lymphocyte receptor diversity?

Answer 4

• • Combinatorial diversification
• • Junctional diversity
• • Somatic hypermutation

Question 5

T/F. The mechanisms accounting for immune diversity for BCR/Antibodies and T-cell/Receptors are IDENTICAL.

Answer 5

True

***Production of heavy chain B cell = Production of Beta chain T cell

Production of light chain B cell = Production of alpha chain T cell

Question 6

T/F. Somatic hypermutation occurs only in T-cells.

Answer 6

False. Somatic hypermutation does not occur in TCRs.

Question 7

Recombination of VDJ segments is directed by what signal?

Answer 7

RSS

Question 8

These are responsible for recombining VDJ segments.

Answer 8

RAG-1
RAG-2

***VDJ recombinase

Question 9

At the junction between D and J segments there is often an insertion of a series of nucleotides which is catalyzed by the enzyme…

Answer 9

TdT

**Junctional diversity

Question 10

TdT catalyzes the random polymerization of nucleotides into DNA without the need for a template. ________ are added to asymmetrically cleaved hairpins in a templated manner. ________ are added in a non-templated manner.

Answer 10

P-nucleotide

N-nucleotide

Question 11

At what stage of B-cell development do surrogate light chains appear then get shut off?

Answer 11

Pre-B cell

Question 12

At what stage do lymphocytes become dependent to self-antigen?

Answer 12

Immature lymphocyte

Question 13

Recombination between VJ and VDJ is not always perfect, it can lead to _________. This can triple the diversity.

Answer 13

Frameshifts

Question 14

In the light chain formation (for B-cells and the Alpha chain of T-cells) explain the formation.

Answer 14

• • DNA between V and J deleted
• • VJ joins
• • mRNA transcribed
• • VJ and C separating mRNA is spliced
• • VJC joins
• • VJC mRNA translated to protein

Question 15

In the heavy chain formation (for B-cells and the Beta chain of T-cells) explain the formation.

Answer 15

• • DNA between D and J deleted
• • DJ joins
• • DNA between V and DJ is deleted
• • VDJ join
• • mRNA transcribed
• • VDJ and C separating mRNA is spliced
• • VDJC joins
• • VDJC mRNA is translated to protein

Question 16

At the junction between D and J segments there is often an insertion of a series of nucleotides which is catalyzed by TdT. What is this process called?

Answer 16

Junctional diversity

Question 17

At what stage of B-cell development are RAG and TdT expressed?

Answer 17

Pro-B to Pre-B

Question 18

What are the surface markers of a pro-B cell?

Answer 18

CD43+
CD19+
CD10+

Question 19

Signals from the ________ are responsible for the largest proliferative expansion of B lineage cells during B cell development.

Answer 19

pre-BCR

***pre-TCR does the same for T cells

Question 20

Signals from the pre-BCR (pre-TCR) signals to irreversibly inhibit rearrangements of the Ig heavy chain (Beta chain) locus on the other chromosome. This is called…

Answer 20

Allelic exclusion

Question 21

This is the term for when an individual B cell can express one heavy chain encoded by only one of the two inherited alleles. It ensures that every B cell will express a single receptor, thus maintaining clonal specificity.

Answer 21

Allelic exclusion

Question 22

B cells and stem cells initially interact through _______ and _______. This promotes another interaction between the stem cell factor (SCF) and ______ leading to proliferation.

Answer 22

VCAM-1
VLA-4
Kit

Question 23

At what stage of B-cell development do they undergo negative selection?

Answer 23

Immature B cells

Question 24

The pre-mRNA can be processed in two ways, one to bring the VDJ next to the _____ gene and the other to bring the VDJ next to the _____ gene. The resulting mRNAs have the LVDJ and ______ or ______ exons.

Answer 24

Cu
Cd

***Will code for a mu or a delta heavy chain

Question 25

T/F. Selection deletes or functionally inactivates cells that display antigen receptors that are self-reactive. Tolerance is acquired by immature B cells that do NOT become activated when challenged with self antigen.

Answer 25

True

Question 26

This occurs in developmentally arrested immature B-cells. RAG protein synthesis remains on for additional rearrangement of light chain genes. If the new light chain is not reactive with self-antigen, then tolerance is established and the B cell will mature.

Answer 26

Receptor editing ***Does NOT occur in T cells, if they are negatively selected then they will undergo apoptosis right away

Question 27

What does the thymus consist of?

Answer 27

``` Thymic cortex (outer cortical region) Medulla (inner cortical region) ```

Question 28

In humans, _______ activity peaks during puberty and declines thereafter.

Answer 28

Thymic

Question 29

The immature T cells contained within the thymus are called _________, and are embedded in epithelial cells called thymic stroma. Express both classes of MHC/HLA.

Answer 29

Thymocytes

Question 30

The thymus is a primary lymphoid organ involved in the production of primary lymphocytes, not antigen presentation. As such, the only route by which progenitor cells enter the thymus and mature T lymphocytes leave is via the ________.

Answer 30

Blood

Question 31

(PRE/IMMATURE) B/T cells express one chain of antigen receptor.

Answer 31

Pre

Question 32

(PRE/IMMATURE) B/T cells express the complete antigen receptor.

Answer 32

Immature

Question 33

Double positive thymocytes undergo selection. This selection occurs with the establishment of self-restriction; recognition of self MHC/HLA.

Answer 33

Positive selection

Question 34

Double positive thymocytes undergo selection. This selection occurs with the establishment of central self tolerance; T lymphocytes do not become activated by self antigen.

Answer 34

Negative selection

Question 35

If there is a strong recognition of either class I or class II MHC + peptide, then the cells will undergo ________ selection.

Answer 35

Negative

Question 36

If there is a weak recognition of either class I or class II + peptide, then the cells will undergo ________ selection.

Answer 36

Positive

Question 37

Small population of self-reactive CD4+ T lymphocytes undergo differentiation to become _______. These function to inhibit self-reactive Th1 cells in the periphery.

Answer 37

Tregs

Question 38

Tregs express both ______ and ______ on their surface, have a unique transcription factor ______.

Answer 38

CD4 CD25 FoxP3