Lymphopoiesis

Question 1

When does the beginning of lymphopoiesis begin and where?

Answer 1

In the foetal liver, first trimester.

Question 2

Where are B cells produced post neonate?

Answer 2

In the marrow from cell progenitors.

Question 3

What happens in the marrow during B cell production?

Answer 3

proliferation

maturation of lymphoblast to lymphocyte that express surface immunoglobulin.

Question 4

What does B cell proliferation produce?

Answer 4

Plasma cells

Question 5

What is the role of plasma cells?

Answer 5

antibody production

humoral immunity.

Question 6

Where are T cells produced?

Answer 6

In the marrow

Question 7

Where do T cells develop?

Answer 7

In the thymus.

Question 8

What do T cells not produce which B cells do?

Answer 8

Antibodies, immunoglobulins.

Question 9

What is the role of the T cells?

Answer 9

• production of cytokines

- cell mediated immunity (cytotoxic, helper, suppressor and memory)

Question 10

What immune response do natural killer cells respond to?

Answer 10

Innate (non-specific) immune response.

Question 11

How do natural killer cells decide which cells to kill? (2)

Answer 11

• kill by antibody dependent cellular cytotoxicity (ADCC)

- Direct killing of cells ex: virus infected cells or tumours cells without the presence of an antibody.

Question 12

What hormone is released from the thymus?

Answer 12

Thymosin.

Question 13

What is the major role of the mature T lymphocyte?

Answer 13

Programmed to recognise one specific type of antigen

Question 14

What type of immunity are T lymphocytes involved in?

Answer 14

Cell mediated immunity

Question 15

What is the major role of the B lymphocyte ?

Answer 15

to provide adaptive antibody-mediated immunity ‘humoral immunity’ ex: plasma cells
- each b lymphocyte targets one specific antigen by producing a specific antibody to attach and enable the destruction of a foreign antigen.

Question 16

What is a speciality in the genes that code for the production of T cells?

Answer 16

These genes that code for the production of B cells (antibodies) - have the facility to slightly change their little segments to give a specific response to whatever threat they come across.

Question 17

What is produced from every one of the millions of different antigens encountered in life?

Answer 17

That there is one corresponding T and B lymphocyte produced in the body.

Question 18

What does cell mediated immunity involve?

Answer 18

As T lymphocytes first encounter - become sensitised to antigen.

• macrophages engulf and phagocytose
• clonal expansion.

Question 19

What needs to happen when a new antigen enters the body?

Answer 19

It needs to be ‘presented’ to the T lymphocyte using APC (diff types incl: macrophages)

Question 20

What do APC do when presenting?

Answer 20

They transport the most antigenic fragment to their own cell membrane and display it on their surface.
On its journey around the body it will come into contact with the T-lymphocyte that has been processed to target the specific foreign antigen.

Question 21

What happens when the antigen has been presented to T-lymphocyte by APC?

Answer 21

Clonal expansion of lymphocyte - 4 different types produced.

Question 22

What are the 4 different types of cells involved in the clonal expansion of the T-lymphocyte?

Answer 22

• memory
• cytotoxic
• helper
• killer

Question 23

What is the role of memory T-cells?

Answer 23

These cells survive past the initial threat and carry the foreign antigen that has been neutralised.

Question 24

What is the role of the cytotoxic T cells?

Answer 24

These directly inactivate any cells carrying antigens by attaching themselves to the target cell and releasing powerful toxins = destruction of the target cell carrying the foreign antigen

Question 25

What is the role of the helper T cell?

Answer 25

These are essential for the correct functioning of not only cell mediated immunity but also antibody mediated immunity

Question 26

what is the more detailed roles of the T helper cells?

Answer 26

• production of cytokines i.e : chemokines, interleukins and interferons - these support and promote cytotoxic T-lymphocytes and macrophages.
• cooperation with B lymphocytes enabling them to produce antibodies.

Question 27

What must be done to B lymphocyte before they can produce antibodies?

Answer 27

They must be stimulated by a helper T lymphocyte first.

Question 28

Where are B lymphocytes found?

Answer 28

Lymphoid tissue - spleen and lymph nodes, also in the blood.

Question 29

What can B lymphocytes do unlike T lymphocytes?

Answer 29

They can bind antigen particles without having to have them presented by APC.

Question 30

Which 2 cells does B lymphocyte clonal expansion involve?

Answer 30

• plasma cells

- memory b cells

Question 31

What is the role of the plasma cells?

Answer 31

To secrete antibodies into the blood to travel around the blood and tissues.

Question 32

How long do plasma cells live for and are they specific?

Answer 32

They live for no longer than a day.

They produce only one type of antibody each which targets specific antigens originally bound to the b lymphocyte.

Question 33

What are the 3 roles of the antibodies produced by plasma cells?

Answer 33

• bind to antigens - labelling them as targets.
• activates complement
• bind to bacterial toxins (neutralising them)

Question 34

What is the role of the memory B cells?

Answer 34

To rapidly respond to another encounter with the same antigen by stimulating the production of antibodies from secreting plasma cells.

Question 35

Why is the balance between immune system and its suppression important?

Answer 35

As the body does not normally develop immunity to its own cells is due to this balance.
Autoimmune diseases are due to this disturbance.