Antigen Recognition by B cell Receptors

Question 1

What are the antigen-recognition molecules for B cells?

Answer 1

immunoglobulin

Question 2

Define an antigen

Answer 2

any substance that can bind an anitbody

Question 3

Define and immunogen

Answer 3

any substance that can elicit an immune response

Question 4

When does the adaptive response occur?

Answer 4

after 96 hours

Question 5

What do T cells recognise?

Answer 5

peptides from pathogens presented by MHC on APCs

Question 6

Role of the variable domain on immunoglobulins

Answer 6

Bind a variety of antigen

Question 7

Role of constant domain of immunoglobulins

Answer 7

Recruits other cells/molecules

Question 8

2 types of light chains

Answer 8

lambda and kappa

Question 9

5 types of heavy chains

Answer 9

M,D,G,A,E

Question 10

How does the C-terminus change between BCR and antibody

Answer 10

hydrophobic in BCR

hydrophilic in antibody

Question 11

Subdivisions of the variable region

Answer 11

Hypervariable region

Framework region

Question 12

Other name for HV regions

Answer 12

Complementarity determining regions (CDRs)

Question 13

Role of the FR regions

Answer 13

Forms a structure which serves as a scaffold to hold the HV resions in position to contact antigen

Question 14

Function of antibodies

Answer 14

To bind pathogens and facilitate their removal

Question 15

Different types of binding sites

Answer 15

• pocket
• groove
• extended surface
• protruding surface

Question 16

What type of chemical force exists between antibody and antigen?

Answer 16

non-covalent

• hydrogen bonds bind over a wide SA
• VDW, electrostatic and hydrophobic add to strength and specificity of binding

Question 17

What can disrupt an antibody-antigen interaction?

Answer 17

high salt conc
extreme pH
detergents
competition

Question 18

What is somatic recombination?

Answer 18

A mechanism of genetic recombination in the early stages of Ig and TCR production of the immune system

Question 19

Process of VDJ recombination

Answer 19

• germline DNA
• D-J rearranges and DNA joined
• V-J or V-DJ joined
• transcription of primary transcript RNA
• splicing to mRNA
• translation

Question 20

Difference between heavy and light chain somatic recombination

Answer 20

light chain is only V-J

Question 21

What guides DNA rearrangement?

Answer 21

Recombination signal sequences (RSS)

Question 22

Enzyme complex that carry out VDJ recombination

Answer 22

VDJ recombinase

Question 23

lymphoid tissue specific enzymes that carry out VDJ recombination

Answer 23

RAG-1 and RAG-2

Question 24

Other enzymes involved in gene rearrangement

Answer 24

• DNA dependent protein kinase (DNA-PK)
• artemis (opens haripin to reveal ssDNA)
• DNA ligase IV (joins DNA ends)

Question 25

Phenotype of RAG, DNA-PK or Artemis knockout mice

Answer 25

• have no functional lymphocytes

SCID (severe combined immune deficiency)

Question 26

RAG1/2 mutation in humans

Answer 26

Omenn syndrome = absence of B cells circulating

Question 27

Artemis defects in humans produce …

Answer 27

Combined immunodeficiency of B and T cells

assoc. with increased radiosensitivity (RS-SCID)

Question 28

Diversity is generated by 4 main processes …

Answer 28

• combinatorial diversity
• junctional diversity
• combo of heavy and light chain V regions
• somatic hypermutation

Question 29

First antibody to be produced in B cell development

Answer 29

IgM

Question 30

3 mechanisms of secondary antigen driven diversification

Answer 30

• somatic hypermutation
• gene conversion
• class switching

Question 31

Which enzymes initiates secondary diversification

Answer 31

acitvation induced cytidine deaminase (AID)