Review Questions

Question 1

How does the K light chain differ from the lambda light chain?

Answer 1

The K light chain has only one C region, the lambda light chain has multiple

Question 2

What introduces the transient hairpin that links the two strands in the VDJ coding region?

Answer 2

RAG-1/RAG-2

Question 3

TLRs differ from scavengar receptors in that they_______

Answer 3

mediate signal transduction pathways and cause cytokine production

Question 4

Which of the following is not a characteristic of mannose-binding lectin (MBL)?
- induced by elevated IL-6 levels.
- acts as an opsonin by binding to mannose-containing carbohydrates of pathogens.
- triggers the alternative pathway of complement activation.
- synthesized by cells in the liver.

Answer 4

triggers the alternative pathway of complement activation.

Question 5

Why do B cells proliferate after H chain rearrangement?

Answer 5

results in the production of many B cells with the same VH chain but different antigen specificities due to different VL regions.

Question 6

Why is the variability in the length (i.e., number of amino acids) of CDR3 important?

Answer 6

some antibodies bind relatively flat surfaces and other antibodies bind deep clefts in the antigen.

Question 7

Which of the following is characteristic of a developing B cell that has reached the “first checkpoint?”

Answer 7

VDJ is successfully rearranged and μ heavy chain polypeptide is made.

Question 8

What does receptor editing allow for?

Answer 8

allows self-specific B cells to repeat somatic recombination of light chains.

Question 9

Imagine you are studying B cell development in a λ5 knock-out mouse. At which stage would B cell development stop?

Answer 9

After VDJ arrangement of H chain, but before VJ recombination of L chain

Question 10

How many different MHC classical class I proteins (i.e., those that present peptides to CD8 T cells) does each nucleated cell in a human heterozygous at the MHC locus express?

Answer 10

6

Question 11

Why is it important for MHC class II molecules to be present in the MIIC when peptides from extracellular antigens arrive in this compartment?

Answer 11

The peptides will degrade quickly if they don’t bind to MHC

Question 12

What is the first checkpoint of T cell development?What is the consequence if the TCR passed the first
check point?

Answer 12

• If TCR b rearrangement is successful, then TCR b pairs with preTa to form the preTCR
• signals from the preTCR result in the thymocyte starting to express CD4 and CD8.

Question 13

Describe what happens during positive selection of T cells, what the cell that has survived positive
selection looks like (list the surface markers)

Answer 13

• If the T cell can successfully weakly bind MHC, it will receive a signal that blocks apoptosis
• It will express CD3, CD4, and CD8

Question 14

What are ICAMs and LFAs, and how would they be important in T cell – HEV interactions?

Answer 14

ICAMs are adhesion molecules that are important for leukocyte homing to infected tissues or secondary
organs, and for cell-cell interactions. They bind to LFA-1.

LFAs are cell adhesion molecules. LFA-1 is an integrin – it is a dimeric protein that are involved in signal
transduction. LFA-1 it binds to the ICAMs.

Question 15

The chemokine CCL21 binds to the CCR7 receptor on naïve T cells and naïve B cells. What role does this
chemokine play in the homing of lymphocytes to the lymph node?

Answer 15

CCL21 is expressed by HEV cells and fibroblast reticular cells in the lymph node. The lymphocytes CCR7
receptor binds to the chemokine, which results in the activation of the integrin on the lymphocyte. This
allows the integrin to bind tightly to the ICAM protein and the lymphocyte arrests. The CCL21 gradient
would allow the lymphocyte to cross the HEV and move into the lymph node.

Question 16

What are HEVs and why are they important?

Answer 16

HEVs are specialized endothelial cells on the blood vessel. They regulate the movement of lymphocytes
into the lymph node. They express CCL21 which binds to its receptor, resulting in the activation of the
integrin. Thus, they make it possible for a lymphocyte to arrest at the entry of the lymph node so that
they can enter into the lymph node.

Question 17

Why can MHC bind to a bunch of different peptides?

Answer 17

or MHC class I, the criteria would be the
correct length and the correct anchor residues (specific amino acids) in the correct location.

For MHC class II, the length of the peptide is more flexible, but the correct anchor residues (specific
amino acids) need to be in the correct location.

Question 18

What is the difference between an antigen presenting cell, and a professional antigen presenting cell?

Answer 18

APCS: co-stimulatory molecules B7.1 and B7.2 that can provide the co-stimulation signal (by binding to CD28) needed to activate T cells.

Question 19

What are two functions of Toll-like receptors (TLRs)?

Answer 19

1. Recognition of a pathogen.
2. Activation of transcription factors via signalling
   pathways so that can result in the expression of pro-inflammatory cytokines, chemokines.

Question 20

What are NOD-like receptors (NLRs) and what types of molecules do they recognize?

Answer 20

intracellular PRRs, similar to TLRs except they are not membrane bound.
They would detect the peptidoglycan of bacteria that have managed to get into the cytoplasm
of the host cell.

Question 21

What happens when NOD-like receptors or RIG-I-like receptors engage their ligand?

Answer 21

They recruit signaling proteins to build signal transduction pathways that lead to
the activation of transcription factors that can result in the expression of pro-inflammatory
cytokines, chemokines and interferons that then go on to contribute to the development of an
effector response.

Question 22

What are the main functions of CRP and MBL and how is this different from other PRRs such as TLRs?

Answer 22

To act as opsonins to enhance phagocytosis and to activate complement to kill the
bacterial pathogen.

They are different than TLRs in that they are soluble extracellular proteins, they do not connect to signal transduction pathways and they execute an effector function directly on the pathogen.

Question 23

How are peptides bound to MHC I proteins

Answer 23

amino acid side chains of the MHC I α chain bind to anchoring residues within the peptide and to the amino group and the carboxyl group at the N and C
termini of the peptide.

Question 24

10. What forms and contexts do you work inside? (for example, within specific cultural contexts,
    academic contexts, traditional contexts, religious contexts, opera, recitals, jazz festivals, symphonic
    works, chamber music, multimedia works, live performance, audio/video works, improvisation,
    experimental contexts, early music or other time periods, devised theatre, interdisciplinary
    collaboration, film and video game music, popular music, folk music, other non-European art music
    repertoires, conference presentations, lectures, artist talks, more-than-human contexts, what else?)
11. How do you relate to those forms? (Do you, for example, participate in them, accept them,
    critique them, perpetuate them, carry them forward, burn them down, dismantle them, break them,
    heal them, revise them, interrupt them, play with them, celebrate them, pay homage to them, what
    else?) In what ways?