Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «T»:
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T (thymine)
T (thymine): In genetics, T stands for thymine, one
member of the A-T (adenine-thymine) base pair in DNA. The
other base pair in DNA is G-C (guanine-cytosine).
Each base pair forms a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a mol...
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T cell
T cell: A type of white blood cell that is
of key importance to the immune system and is at the core of adaptive immunity, the system that tailors the body's immune response to specific pathogens. The T cells are like soldiers who search out and destroy the targeted invaders.
Immature T cells (terme...
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T cell, peripheral
T cell, peripheral: A T cell found in the
peripheral blood rather than in the lymphatic system.
...
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T lymphocyte, cytotoxic
T lymphocyte, cytotoxic: See: Cytotoxic T-lymphocyte....
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T-4 cell
T-4 cell: A type of T cell that has CD4 markers on its surface and participates in the immune response by recognizing foreign antigens and secreting substances called cytokines that activate T and B cells. T-helper cells fall into two main classes: those that activate other T cells to achieve cellu...
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T-4 count
T-4 count: A test that counts the number of T-
4 cells in the blood, usually to assess the immune status
of a patient with the HIV virus (AIDS). It's important to
note that there are also T-4 cells in the lymphatic system,
and they may be more severely affected there than in the
bloodstream. Of...
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T-8 cells
T-8 cells: T cells that express the CD8
transmembrane glycoprotein (CD8+ T cells). They close down
the immune response after invading organisms are destroyed.
Suppressor T cells are sensitive to high concentrations of
circulating lymphokine hormones, and release their own
lymphokines after an ...
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T-cell depletion
T-cell depletion: Treatment designed to destroy T cells, which play an important role in the immune response. Elimination of T cells from a bone marrow graft from a donor may reduce the chance of graft-versus-host disease (an immune reaction against the recipient's tissues)....
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T-cell leukemia
T-cell leukemia: A disease in which certain cells of the lymphoid system called T lymphocytes or T cells are malignant. T cells are white blood cells that normally can attack virus-infected cells, foreign cells, and cancer cells and produce substances that regulate the immune response....
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T-cell lymphoma
T-cell lymphoma: A disease in which cells in the lymphoid system called T cells (or T lymphocytes) become malignant. T-cell lymphomas account for a minority (about 15%) of non-Hodgkin lymphomas in the US and are more common in Asia.
The T-cell lymphomas are highly diverse and include lymphoblastic l...
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T-cell receptor
T-cell receptor: A device used by T cells
for recognizing specific antigens. T cells have receptors
that are activated exclusively by a target antigen.
...
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T-helper cell
T-helper cell: A type of T cell that provides help to other cells in the immune response by recognizing foreign antigens and secreting substances called cytokines that activate T and B cells. T-helper cells fall into two main classes: those that activate other T cells to achieve cellular inflammator...
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T-suppressor cell
T-suppressor cell: A type of immune cells, also called
T8 cells, these cells close down the immune response after it has destroyed invading
organisms. T8 cells are sensitive to high concentrations of circulating lymphokine
hormones and release their own lymphokines after an immune response has achie...
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T-suppressor cells
T-suppressor cells: T cells that express the CD8
transmembrane glycoprotein (CD8+ T cells). They close down
the immune response after invading organisms are destroyed.
Suppressor T cells are sensitive to high concentrations of
circulating lymphokine hormones, and release their own
lymphokines a...
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T-suppressor count
T-suppressor count: A test that counts the
number of T-suppressor (T-8) cells in the bloodstream. It
appears that some T-8 cells secrete a substance that can
kill the HIV virus, so a high count is believed to be a
good indicator for people with HIV (AIDS). See also T-
suppressor cells....
