Chapter 4: Antigen recognition in adaptive immune system

Question 1

What are complementarity determining region (CDR) for antibodies?

Answer 1

3 variable antigen-binding loops at the end termini

Question 2

What antibodies are on naive B cells?

Answer 2

IgD
IgM

Question 3

What are the 5 types of C regions of heavy chains?

Answer 3

IgA
IgD
IgE
IgG
IgM

Question 4

What does the antibodies ability to have cross reactivity mean for the immune system?

Answer 4

could cause an allergic reaction

Question 5

How are hybridomas and monoclonal antibodies made?

Answer 5

using spleen cells from a mouse and fusing them with mutant immortal myeloma cell lines

Question 6

What can depletion of B cells lead to?

Answer 6

rheumatoid arthritis
multiple schlerosis
other autoimmune diseases

Question 7

What can blocking IgE lead to?

Answer 7

allergy-related asthma

Question 8

What do the alpha chains of T cell antigen receptors recognize?

Answer 8

the antigen and the MHC class I molecule

Question 9

What is the on/off rate for immunoglobulin (Ig)?

Answer 9

rapid on rate
variable off rate

Question 10

What is the on/off rate for T cell receptor (TCR)?

Answer 10

slow on rate
slow off rate

Question 11

Are immunoglobulins or TCRs made up of three CDRs on each side?

Answer 11

Both!
- immunoglobulins have 3 CDRs on the heavy chain and the light chain
- TCRs have 3 CDRs on the alpha and beta chains

Question 12

The affintiy increases during an immune response for immunoglobulins or T cell receptors?

Answer 12

Immunoglobulin

Question 13

Are T cell receptors (TCR) or immunoglobulins dependent on MHC molecules?

Answer 13

TCR

Question 14

What are the steps in maturation of T/B cells?

Answer 14

1. common lymphoid progenitor cell
2. pro-B/T cells (failure to express this and die)
3. Pre-B/T cell expresses antigen receptor (failure to express this and die)
4. immature B/T cell expresses complete antigen receptor
   a. If weak antigen recognition then positive selection and mature T/B cell forms
   b. If strong antigen recognition then negative selection and cell death

Question 15

What does it mean if the immature B/T cell has strong antigen recognition?

Answer 15

self-reactive and will undergo negative selection

Question 16

How does recombination and expression of immunoglobulin genes work?

Answer 16

• somatic recombination (D-J joining)
• somatic recombination (V-DJ joining)
• transcrition
• RNA splicing
• translation

Question 17

What are the mechanisms of diversity in antigen receptors?

Answer 17

• combinatorial diversity
• junctional diversity
• Enzyme mediating recombination is a lymphoid specific recombinase plus repair enzymes to heal the double strand breaks created in the process

Question 18

To select for B lymphocytes what is the process?

Answer 18

• stem cell
• Pro-B
• recombined H chain gene (Pre-B)
• recombined H chain gene, K or lamba genes (immature B)
• alternative splicing of primary transcript (mature B)

Question 19

What are the steps in maturation and selection of MHC-restricted T lymphocytes?

Answer 19

• stem cell
• double negative (pro T cell)
• pre T cell
• double positve (immature T cell)
  a. weak recognition of class II = positive selection for CD4+
  b. weak recognition of class I = positive selection for CD8+
  c. no recognition of MHC = failure of positive selection and death by neglect
  d. strong recognition of either class I or class II = negative selection (self reactive)

Question 20

_____ chain recombination is first to create pre-TCR

Answer 20

Beta

Question 21

Where are pro B/T cells proliferated?

Answer 21

bone marrow