I understand that the acquired immune system is basically lymphocytes. B-Lymphocytes (matured in bone marrow) and T-Lymphocytes (matured in thymus).
B-Lymphocytes make antibodies (after differentiating into gamma globulin/plasma protein) and T-Lymphocytes destroy cells by cell mediation(?) (not phagocytosis).
Here's what I don't understand....clonal selection.
When an antigen is recognised by specific lymphocytes, that particular lymphocyte clones itself. The lymphocyte that clones itself, is it purely just a lymphocyte or a B-Lymphocyte or a T-Lymphocyte or BOTH?
Then they differentiate into either memory or effector cells.
Effector cells destroy the foreign antigen. Because these two effector lymphocytes attack in different ways (B produce antibodies and T kill by cell mediation(?)), how do you get separate B and T Lymphocyte effector cells?Do the effector cells then differentiate again into T-Lymphocyte effectors and B-Lymphocyte effectors?
Are the memory cells B-Lymphocytes or T-Lymphocytes or just memory cells?
Please help me understand the acquired immune system. Watch
- Thread Starter
- 29-12-2010 14:53
- Thread Starter
- 29-12-2010 15:09
- 29-12-2010 15:27
The B cells become sensitised by an antigen to produce antigen specific antibody.
The antibody is a complex protein molecule which can also be detected on blood tests as a plasma protein.
Gamma globulin is the name given to a blood product which contains antibody and it is used with caution in modern medicine to provide short term protection against some infections.
The antibodies may destroy antigens (for example on the viral cell surface) in a number of ways- for example by coating it and neutralising it (opsonisation) so it cant enter and replicate in another cell, or by coating the antigen and making it easy for another cell to engulf (phagocytose) and kill (lyse)
When a B cell which has already been sensitised by a specific antigen to produce specific antibody multiplies this is called clonal selection. Clonal selection can be stimulated by T helper cells.
Memory cells can be
B lymphocyte cells - which can therefore produce antigen specific antibody very quickly
or T lymphocyte cells- which can produce an antigen specific effector cell response very quickly : very simply this can include a killer (cytotoxic ) cell response, a helper (cytokine) cell response which helps to attract more killer cells to the antigen, and/or stimulates the B cells to clone, and other types of effector cell response (still being researched and more detail available in textbooks)
T memory cells are stem cells which live in the bone marrow and self replicate. It is how your body remembers infections it came across in childhood.
Cloning in this context usually refers to the cloning of B lymphocytes which have been sensitised by antigens to produce specific antibodies.
Hope this helps
- 30-12-2010 19:06
tbh, no one truly understands how clonal selection works fully - it can get very complicated! Trying to keep it basic, both T cells and B cells can be the first ones to bind the antigen, but usually need to work together to produce a response (this reduces the chance of autoimmunity). Other factors, like the presence of 'danger signals', can also be important, plus there are other Antigen Presenting Cells which are commonly the way the specific B or T cell ends up in contact with the anitgen (in lymph nodes).Last edited by nexttime; 30-12-2010 at 19:08.