Lymphopoiesis Flashcards
When does the beginning of lymphopoiesis begin and where?
In the foetal liver, first trimester.
Where are B cells produced post neonate?
In the marrow from cell progenitors.
What happens in the marrow during B cell production?
proliferation
maturation of lymphoblast to lymphocyte that express surface immunoglobulin.
What does B cell proliferation produce?
Plasma cells
What is the role of plasma cells?
antibody production
humoral immunity.
Where are T cells produced?
In the marrow
Where do T cells develop?
In the thymus.
What do T cells not produce which B cells do?
Antibodies, immunoglobulins.
What is the role of the T cells?
- production of cytokines
- cell mediated immunity (cytotoxic, helper, suppressor and memory)
What immune response do natural killer cells respond to?
Innate (non-specific) immune response.
How do natural killer cells decide which cells to kill? (2)
- kill by antibody dependent cellular cytotoxicity (ADCC)
- Direct killing of cells ex: virus infected cells or tumours cells without the presence of an antibody.
What hormone is released from the thymus?
Thymosin.
What is the major role of the mature T lymphocyte?
Programmed to recognise one specific type of antigen
What type of immunity are T lymphocytes involved in?
Cell mediated immunity
What is the major role of the B lymphocyte ?
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.
What is a speciality in the genes that code for the production of T cells?
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.
What is produced from every one of the millions of different antigens encountered in life?
That there is one corresponding T and B lymphocyte produced in the body.
What does cell mediated immunity involve?
As T lymphocytes first encounter - become sensitised to antigen.
- macrophages engulf and phagocytose
- clonal expansion.
What needs to happen when a new antigen enters the body?
It needs to be ‘presented’ to the T lymphocyte using APC (diff types incl: macrophages)
What do APC do when presenting?
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.
What happens when the antigen has been presented to T-lymphocyte by APC?
Clonal expansion of lymphocyte - 4 different types produced.
What are the 4 different types of cells involved in the clonal expansion of the T-lymphocyte?
- memory
- cytotoxic
- helper
- killer
What is the role of memory T-cells?
These cells survive past the initial threat and carry the foreign antigen that has been neutralised.
What is the role of the cytotoxic T cells?
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
What is the role of the helper T cell?
These are essential for the correct functioning of not only cell mediated immunity but also antibody mediated immunity
what is the more detailed roles of the T helper cells?
- 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.
What must be done to B lymphocyte before they can produce antibodies?
They must be stimulated by a helper T lymphocyte first.
Where are B lymphocytes found?
Lymphoid tissue - spleen and lymph nodes, also in the blood.
What can B lymphocytes do unlike T lymphocytes?
They can bind antigen particles without having to have them presented by APC.
Which 2 cells does B lymphocyte clonal expansion involve?
- plasma cells
- memory b cells
What is the role of the plasma cells?
To secrete antibodies into the blood to travel around the blood and tissues.
How long do plasma cells live for and are they specific?
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.
What are the 3 roles of the antibodies produced by plasma cells?
- bind to antigens - labelling them as targets.
- activates complement
- bind to bacterial toxins (neutralising them)
What is the role of the memory B cells?
To rapidly respond to another encounter with the same antigen by stimulating the production of antibodies from secreting plasma cells.
Why is the balance between immune system and its suppression important?
As the body does not normally develop immunity to its own cells is due to this balance.
Autoimmune diseases are due to this disturbance.
