Adaptive immunity

Question 1

Which cells are involved in the adaptive immune system?

Answer 1

T cells
B cells
Dendritic cells

Question 2

Give an example of clonal variation

Answer 2

Billions of ready-made identical neutrophils

Question 3

Give an example of clonal selection

Answer 3

Billions of different B cells that require several days of differentiation

Question 4

What happens when a B cell detects an antigen?

Answer 4

Rapid proliferation of lymphocytes

Lymphocytes produced are clones and are specific

Question 5

What is an antigen?

Answer 5

Any molecule that is specifically recognised by T cells or antibodies

Question 6

What is an epitope?

Answer 6

The site on the antigen that binds directly to the antibody or T cell

Question 7

What is a T cell antigen?

Answer 7

A peptide derived from an antigenic protein

Question 8

What is a B cell antigen?

Answer 8

A protein or carbohydrate

Question 9

What are the two parts to an antibody molecule?

Answer 9

The antigen receptor (variable region)
The effector (constant region)

Question 10

What is the structure of a T-cell receptor?

Answer 10

Variable region

Membrane bound constant region

Question 11

What creates a diverse range of T and B cell receptors?

Answer 11

Random genetic recombination

Question 12

What is the estimated number of possible T and B cells?

Answer 12

100 billion

Question 13

What is the normal activity of B and T cells in the body?

Answer 13

They constantly circulate the body through the lymph nodes, lymphatic vessels and blood vessels
This increases the chance of them detecting an antigen

Question 14

Describe immunoglobulin structure

Answer 14

Two heavy chains and two lights chains

Bonded by disulphide bridges

Question 15

What does the heavy chain determine?

Answer 15

The function of the antibody

Question 16

Immunoglobulins form part of the structure of B cell receptors. What is the other component?

Answer 16

CD79 A+B

Question 17

What do plasma cells release?

Answer 17

Plasma cells release immunoglobulins as antibodies

Question 18

Name the three roles of antibodies

Answer 18

Neutralisation
Opsonisation
Complement activation

Question 19

What is the purpose of neutralisation?

Answer 19

The antibody prevents bacterial adherence

Question 20

What is the purpose of opsonisation?

Answer 20

The antibody promotes phagocytosis

Question 21

What is the purpose of compliment activation?

Answer 21

Antibody activates complement
Enhances opsonisation
May lyse the bacteria

Question 22

Which cell pathway are antibodies involved in?

Answer 22

The antibody triggers C1q which then activates CD3

Question 23

Describe B cell development

Answer 23

Naive B cell develops in bone marrow

Question 24

Describe B cell development

Answer 24

B cell matures in bone marrow
B cell detects antigen and is activated
Memory B cells are produced
Plasma cells are produced

Question 25

What is a plasma cell?

Answer 25

A cell that produces specific antibodies in response to an infection

Question 26

Outline T cell development

Answer 26

``` T cell precursor made in bone marrow, migrates to thymus Thymus produces CD4 and CD8 cells These circulate the body Detect antigen Develop into effector or memory T cells ```

Question 27

What must an antigen be presented on for it to be recognised by a T cell?

Answer 27

A MHC protein

Question 28

Why must an antigen be presented on a MHC protein?

Answer 28

The epitope is usually hidden within the peptide The antigen must be fragmented The epitope then binds to MHC where it can be recognised

Question 29

What activates a naive T cell

Answer 29

A dendritic cell

Question 30

What does a CD4+ T cell recognise?

Answer 30

Epitopes bound to a class II MHC protein

Question 31

What does a CD8+ T cell recognise?

Answer 31

Epitopes bound to a class I MHC protein

Question 32

``` What do the following T cell helpers do? Th1 cell Th2 cell Th17 cell Tfh cell ```

Answer 32

Th1 cells provide signals to macrophages Th2 cells provide signals to B cells (production of IgE) Th17 is responsible for inflammation Tfh support B cell differentiation

Question 33

``` Describe the functions of these antibodies IgM IgA IgG IgD IgE ```

Answer 33

``` IgM is produced early in immune response IgA is secreted to mucous membranes IgG has the highest serum concentration IgD is a membrane receptor IgE is mainly localised on mast cells ```

Question 34

How does the action of CD4+ and CD8+ cells differ?

Answer 34

CD4+ cells recruit macrophages CD8+ cells trigger apoptosis They referred to as cytotoxic T cells

Question 35

What is the action of a cytotoxic T cell?

Answer 35

The cell binds to virus-infected cell Programs cell death by DNA fragmentation Moves to next target Cell dies by apoptosis