our p b p n blog.
this is : liveric.blogspot.com
A blog set up for the subject
Principles of Biochemistry & Physiology for Nutrition (PBPN)
by students of A7A1
just for Mdm Kalpana!:D
Our Question:
Our immune system tends to mount an immune response to the entry of an antigen from the same species (e.g. renal transplant).
- Discuss on the factors to be considered to prevent renal transplant rejection.
- Artificial implants (like pace makers, knee/hip joints?) and corneal transplants are not rejected by our immune system? Why?
Topic of Discussion:
* What is Immune System and How Does It Work?
* Renal Transplant Rejection
* Artificial implants and Corneal Transplants
* Q&A Session
* Interesting Facts!!
* Glossary
navigations are on top.=)
Monday, February 9, 2009
Topic:
What is Immune System and How Does It Work?
How Does It Work?
The body's immune system is responsible for defence against foreign substances or called antigen such as bacteria, viruses, parasites and fungi which cause diseases. Once these antigens enter the body, immune system will be triggered to release antibodies which in turn destroy them. Our immune system does not try to attack our own body cells because it is able to differentiate between our body's own cells (self) and foreign cells (non-self). Hence, tissues or cells from other person can be recognised as non-self and this explains why tissue rejection occurs in organ transplant such as renal transplant.
Autoimmune disease
In abnormal condition, the immune system can identify self as non-self and launch an attack against our own body cells. This is called autoimmune disease.
B Cells & T Cells
Lymphocytes or white blood cells are the key role in the immune system' defence mechanism and they are produce by lymphoid organs which can be found throughout the body. Besides travelling via blood vessels, lymphocytes can also travel through the lymphatic vessels which carry lymph th
at surrounds the body's tissues.
B cells and T cells are the main type of lymphocytes. The role of B cells is to produce antibodies and to fight bacterial infections. When B cells encounter an antigen, they give rise to many large plasma cells which produces antibodies. Each B cell is specific to produce only one type of antibody. The antibody which attacks viruses for influenza is different from antibody that attacks bacterium for pneumonia and these antibodies come from different B cells.
On the other hand, T-cells play a role in fighting viruses and organ rejection in transplant patients.They have receptors on their surfaces which recognise non-self marker. There are 2 major types of T cells namely Helper T Cells (Th Cells) and Killer T Cells also known as Cytotoxic T lymphocytes or CTLs.
Helper T cells act by coordinating immune response by communicating with other cells such as stimulating B cells to produce antibodies and activating T cells while killer T cells directly attack non-self target.
Major Histocompatibility Complex (MHC) Molecules
MHC molecules are proteins recognised by T cells when distinguishing between self and non-self (National Cancel Cell Institute, 2003). T cells only recognise and act on antigen if it is carried on the surface of self MHC molecules. In other words, self MHC molecules bring antigen to T cells so that the T cells will attack it.
MHC molecules are present in almost every cell surface in our body and the MHC molecules of one person differs from another person's. Due to this difference in MHC molecules, organ transplantation becomes difficult as doctor has to find the closest compatibility of MHC molecules between the recipient's organ and the donor. Otherwise, the recipient's T cells will launch an attack against the transplanted organ which lead to rejection.
Natural Killer (NK) cel
ls
They are lymphocytes that recognise and act on antigen in cells that lack self MHC molecules. Hence, they are capable in the destruction of many types of antigen or foreign cells.
Reference:
National Cancer Institute and NIAID(2003) Understanding the Immune System:How It Work
Extracted From:
http://www.niaid.nih.gov/Publications/immune/the_immune_system.pdf
