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What is a T Cell?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

A T cell is a type of lymphocyte or white blood cell which is involved in the function of the immune system. T cells can bind to various cells in the body to kill off infected cells and attack antigens which could cause someone to get sick. A decline in the level of T cells can indicate that someone is suffering from a disease which causes immune suppression, or that someone is taking medications which suppress the functions of the immune system, as is done to prepare for organ transplants.

These cells originate in the bone marrow, working their way into a gland called the thymus, where they mature: the "T" in "T cell" comes from "thymus." In the thymus, the cells differentiate into different types of T cells such as helper cells, natural killer cells, regulatory cells, and cytotoxic cells. These cells in turn travel through the bloodstream to look for signs of unwanted invaders, at which point the cells swing into action to neutralize or destroy the invaders they have identified.

A T cell is a type of lymphocyte, a white blood cell.
A T cell is a type of lymphocyte, a white blood cell.

Another important event occurs in the thymus when T cells mature. The thymus goes through a process known as “negative selection,” in which T cells which could trigger autoimmune responses are allowed to die off. This is designed to prevent the immune system from attacking the body by accident. Sometimes this process goes awry, causing autoimmune conditions which can cause severe medical problems.

The thymus goes through a process of "negative selection” in which T cells are allowed to die off.
The thymus goes through a process of "negative selection” in which T cells are allowed to die off.

A T cell can do all sorts of things, depending on which type it is. Some bind to cells and kill them if the cells have become infected, while others store the memory of specific antigens so that the body can respond quickly if these antigens are identified. Helper T cells identify situations in which an immune system response is needed, and trigger the release of various signals to the rest of the body. Regulatory T cells mop up in the aftermath of an infection, taking care to remove cells which have developed autoimmune responses.

Chronic alcohol abuse may lead to the reduced function of T-cells in the body.
Chronic alcohol abuse may lead to the reduced function of T-cells in the body.

In individuals with suspected immune conditions, a doctor may request a test which is designed to count the T cells and to identify numbers of particular types. CD4 cells, for example, are a kind of T cell which decline radically in patients with HIV. In people of normal health, the CD4 count is usually above 1,000, while AIDS patients have 200 or fewer CD4 cells in their blood tests. If a test reveals that a patient has an unusually low T cell count, the doctor needs to determine why, and formulate a plan of action for addressing the issue.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

anon990438

just to let the world know, drinking your urine is the best way to stay healthy, simply because your t cells, that are made in the marrow bone are super charged to keep the body clean.

Now when you urinate out your liquid, drink it, and remember what you are doing. The t cell is made in the marrow and it comes from the essence of life first, then into your body, but don't do the urine healing if you have metal fillings in your mouth; your urine is so good that it will remove them.

Plus, make sure you have your diet in good shape for four or five days before you start. Then your urine will be the nicest drink you have ever had. Remember your body is a free energy device, and drinking the urine is the hidden secret that someone doesn't want you to know about. Share this knowledge and do your part to help people remember the truth of what they are.

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    • A T cell is a type of lymphocyte, a white blood cell.
      By: apple1
      A T cell is a type of lymphocyte, a white blood cell.
    • The thymus goes through a process of "negative selection” in which T cells are allowed to die off.
      By: designua
      The thymus goes through a process of "negative selection” in which T cells are allowed to die off.
    • Chronic alcohol abuse may lead to the reduced function of T-cells in the body.
      By: BlueSkyImages
      Chronic alcohol abuse may lead to the reduced function of T-cells in the body.
    • T cells mature in the thymus gland.
      By: reineg
      T cells mature in the thymus gland.
    • A blood smear may be used to check a person's T cell count and ensure they are working properly.
      By: toeytoey
      A blood smear may be used to check a person's T cell count and ensure they are working properly.
    • A low level of T cells may indicate that an HIV test should be performed.
      By: jarun011
      A low level of T cells may indicate that an HIV test should be performed.
    • Without immunosuppressants, the body views an organ transplant -- heart, kidneys, liver, lungs and pancreas, for example -- as foreign.
      By: rob3000
      Without immunosuppressants, the body views an organ transplant -- heart, kidneys, liver, lungs and pancreas, for example -- as foreign.