T - CELL -
Noun: An abbreviation for T-Lymphocyte Cell. It is a white blood cell produced in the bone marrow or in the Lymph glands which has made its way through the body to the Thymus gland which is located in the chest which is what gives it the name T Cell. There it matures into a type of lymphocyte called a T cell. From here it circulates in the blood, spleen and particularly the lymph glands. The T-cells provide protection against certain bacteria, viruses, and other disease-causing organisms that have already infected a cell and are growing inside the cells of the body. As these foreign bodies are inside our cells multiplying or doing their damage, they are hidden from the antibodies made by the B cells. But the T cells can recognise an infected cell and will attack it and thereby destroy the hidden intruder. The T cells work together with the B cells and the macrophages during an immune response. T cells attract macrophages to the intruder and greatly stimulate the process of phagocytosis . In addition, B cells will produce far more antibodies if the T cells are present. See picture of White blood cell

T-cells are divided into four groups:

Helper T-Cells - (also called TH, T4 or CD4 cells) help other cells destroy infective organisms. They do not attack invading micro-organisms but decide whether it is a threat and whether to switch the immune system on. They can order the B-cells into action. They point out foreign antigens to the B-cells which in turn manufacture a Y shaped protein called an " immunoglobulin " or "antibody". The antibody zeroes in on the antigen and attaches to the surface of the invading cell. The "Aids virus" tends to invade the helper cells, and when the helper cells are no longer functioning, the bodies immune system does not get switched on even though there is a major invasion taking place.

Suppressor T-Cells - (also called TS, T8 or CD8 cells) also do not attack invading micro-organisms but switch off both the B and T lymphocytes attack when an infection has passed and recovery is complete so the aggressive T-cells don't destroy normal tissue.

Killer T-Cells - (also called cytotoxic T lymphocytes, or CTLs), recognise and destroy abnormal or infected cells once it has received permission from a helper T-cell. Most of the body's white cells will recognise other "self" cells and leave them alone but with the assistance of "Helper T cells", Killer T cells seek out and destroy any of the body cells that have hidden micro-organisms within them. Killer T cells use a very strong enzyme against the infected cell to destroy it. The action of Killer T cells stimulates an increase in macrophage activity to clear up the debris.

Natural Killer Cells - (NK) cells are actually primitive T-cells that are free to attack indiscriminately without requiring permission from a helper T-cell. This makes them the immune system's first line of defense. Since they lack receptors for identifying antigens, NK cells work best when their target has first been identified by macrophages and helper T-cells. These cells release the chemical messenger interferon which attracts and stimulates NK cells, causing them to grow larger and more aggressive. NK cells also zero in readily on targets that have already been coated with antibodies such as tumor cells and body cells infected with a virus. NK cells swiftly migrate through the bloodstream to such targets which they immediately kill with their toxic enzymes.

If a patient has AA or MDS , whether immunosuppressive therapy is given or a bone marrow transplant , the T cells will be killed off with drugs as part of the therapy. This will greatly reduce the patients immune system so everything possible must be done to avoid infections.

This site looks much better in a browser that supports current web standards, but it is accessible to any browser. Download one now