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Topic: T cell

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  T cell definition - Medical Dictionary definitions of popular medical terms easily defined on MedTerms
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.
Immature T cells (termed T-stem cells) migrate to the thymus gland in the neck, where they mature and differentiate into various types of mature T cells and become active in the immune system in response to a hormone called thymosin and other factors.
T cells can produce substances called cytokines such as the interleukins which further stimulate the immune response.
www.medterms.com /script/main/art.asp?articlekey=11300   (457 words)

  B Cells and T Cells
T cells is to monitor all the cells of the body, ready to destroy any that express foreign antigen fragments in their class I molecules.
T cells bind an epitope consisting of an antigen fragment lying in the groove of a class II histocompatibility molecule.
T cells have receptors (TCRs) that bind to antigen fragments nestled in MHC molecules.
users.rcn.com /jkimball.ma.ultranet/BiologyPages/B/B_and_Tcells.html   (1889 words)

  Helper T cell
cells secrete cytokines, proteins or peptides that stimulate other lymphocytes[?]; the most common is interleukin-2[?] (IL-2), which helps B cells differentiate into plasma B cells.
cells are specific to the antigen they first encountered and can be called upon during the secondary immune response[?].
cells have present on the cell surface the protein CD4[?], which is attracted to portions of the Class II MHC molecule.
www.ebroadcast.com.au /lookup/encyclopedia/he/Helper_T-cell.html   (124 words)

 T helper cell Summary   (Site not responding. Last check: )
T cells are generally treated as having a pre-defined role as helper T cells within the immune system, although there are known rare exceptions.
T cells far more efficiently (likely due to a change in the co-receptors it binds to during infection), and the immune system is overwhelmed.
T cell population is too small to recognise the full range of antigens that could potentially be detected.
www.bookrags.com /T_helper_cell   (3706 words)

 T cell Summary   (Site not responding. Last check: )
Cells that react with the body's own proteins are eliminated by a process known as "clonal deletion." The process of clonal deletion ensures that the mature T cells, which circulate in the blood, will not interact with or destroy an individual's own tissues and organs.
T cells are a type of white blood cell that play a central role in cell-mediated immunity.
Regulatory T cells, formerly known as suppressor T cells, are crucial for the maintenance of immunological tolerance.
www.bookrags.com /T_cell   (2068 words)

 Transcriptional regulator Id2 mediates CD8+ T cell immunity - Nature Immunology
T cells did not accumulate because the cells were highly susceptible to apoptosis.
T cells responding to infection had changes in the expression of genes that influence survival and had altered memory formation.
T cells and the magnitude of effector responses, suggesting a mechanism involving Id protein– and E protein–mediated survival and differentiation of mature T cells.
www.nature.com /ni/journal/v7/n12/abs/ni1403.html;jsessionid=DBAA0F65EE0963D5C3E9BA468C16DC48   (317 words)

 T Cell Deficiencies
The T cell areas in the lymph nodes are depleted and there is usually a mild lymphopenia; the thymic shadow may be absent in a lateral chest x-ray.
Blood lymphocytes are not reactive to the T cell mitogens concanavalin A or phytohemagglutinin.
The T cells are not responsive in vitro to the normal T cell mitogens.
www.lib.mcg.edu /edu/esimmuno/ch12/tcelldef.htm   (646 words)

 T Cell Activation
Studies of the response of T cells from a TCR-transgenic mouse line showed that the aging defect applied to naive T cells and to peptide antigens as well as to responses to stronger, polyclonal activators like antibodies to the CD3 complex.
The failure of aged T cells to initiate cytoskeletal changes shows that their defect lies at a stage prior to recognition, by the T cell receptor, of the specific residues that distinguish agonist from antagonist peptides.
Treatment of aged T cells with an endopeptidase specific for O-linked sugars (such as those on CD43) was indeed found to restore excellent synapse formation to T cells from old mice, and to restore production of surface activation markers CD69 and IL-2R as well [PubMed].
www-personal.umich.edu /~millerr/T_cell_activation.htm   (1482 words)

 BioCarta - Charting Pathways of Life
T helper cells play an essential role coordinating the activities of other parts of the immune system, including B cells, cytotoxic T cells, macrophages and other cells.
The crucial nature of helper T cells in the normal immune response is demonstrated by the severe immune deficiency associated with the HIV-induced helper T cell depletion.
Like all T cells, helper T cells express T cell receptors complexed with the CD3 proteins that are responsible for the recognition and response of the cell to specific antigens (see “T Cell Receptor Signaling Pathway”).
www.biocarta.com /pathfiles/h_thelperPathway.asp   (352 words)

 Skin Research Center: Immunobiology of Cutaneous T Cell Lymphoma - Dermatology   (Site not responding. Last check: )
CD8 T cell lines, reacting selectively with the tumor cells, were propagated by incubation with the CTCL cells of the same patient in the presence of interleukin-2.
Heald, Edelson, Tigelaar, and Picker (UT Southwestern) demonstrated that the malignant cell in CTCL is a CD45RO+ ("memory"-type) CLA+ T cell.
Girardi' studies are analyzing the relative roles of T cell subsets in the oncogenesis, tumor surveillance, and tumor rejection of SCC by utilizing the crossbreeding of genetically engineered mice.
info.med.yale.edu /dermatology/src/guides/cutaneoustcell.html   (2991 words)

 Research News: Scientists Create a New Way to Study T Cell Signaling
This signal must be enhanced and sustained long enough for the T cells to commit to mounting an immune response, and then must be cut off in time to avoid antigen-induced cell suicide or “apoptosis” of the T cells.
It has also been established that the control center for T cell signaling is at the junction or point of contact between T cells and antigens, dubbed the “immunological synapse” because it resembles the synapse between two communicating nerve cells.
T cell receptors (TCRs) are communicating with their corresponding signaling ligands on the membrane.
www.lbl.gov /Science-Articles/Archive/PBD-TCR-signaling.html   (1259 words)

 MedFriendly.com: T cell
A T cell is a type of white blood cell that directs the body’s immune (defense) system to defend against bacteria and other harmful cells.
B cells are types of white blood cells that have the ability to recognize antigens, which are substances located on the surface of invading microorganisms (e.g., bacteria).
T cells that perform this function are known as suppressor T cells or regulatory T cells.
www.medfriendly.com /tcell.html   (659 words)

 Immune System: T Cell Immunity
T cells are of two types: helper T cells (which have a marker on their cell surface called CD4) and killer T cells (which have the CD8 marker on their surface).
Individual T cells are targeted against the specific antigen signatures of viruses and bacteria, and when helper T cells encounter their specific antigens, they become activated and quickly expand in number.
T cells have receptors on their surfaces that recognize HLA (human leukocyte antigen) markers that are present on all body cells.
www.personalmd.com /news/tcells_10312000.shtml   (573 words)

 Dictionary of Cancer Terms - National Cancer Institute
T cells also produce a number of substances that regulate the immune response.
Elimination of T cells from a bone marrow graft from a donor may reduce the chance of an immune reaction against the recipient's tissues.
T describes the size of the tumor and whether it has invaded nearby tissue, N describes any lymph nodes that are involved, and M describes metastasis (spread of cancer from one body part to another).
www.cancer.gov /dictionary/db_alpha.aspx?expand=T   (5945 words)

 T cells
T cell differentiation into Th1 and Th2 cells after activation is not considered as part of T cell Development, but part of the normal immune response.
T cell precursors however arrive to the thymus from the Bone Marrow.
The stages of T cell development are identified by the expression of specific cell surface markers, such as TCR (T Cell Receptor), CD3 (which serves as the signal transduction component of TCR), and CD4/CD8.
sprojects.mmi.mcgill.ca /immunology/spec_imm_cells.htm   (767 words)

 eMedicine - T-Cell Disorders : Article by Richard H Huggins, MD
The nomenclature for T lymphocytes is based on the role of the thymus in the differentiation and maturation of T lymphocytes.
Pathophysiology: Mature functional T cells undergo differentiation and maturation in the thymus; therefore, the thymus is critical for intact cell-mediated immunity.
The ability of T cells to recognize and respond appropriately to antigen depends on a complex pathway of surface glycoproteins and transmembrane molecules involved in signal transduction, many of which can be ascertained by flow cytometry using monoclonal antibodies directed against these antigens.
www.emedicine.com /ped/topic2212.htm   (7663 words)

 T Cell Development
T cell precursors enter the subcapsular cortical areas, where they encounter networks of cortical epithelial calls (the thymic stroma) and undergo a period of proliferation.
Presumably these self-specific T cells were positively selected due to their strong binding to Class II rather than to peptide, so that binding to syngeneic Class II bearing different self peptides still occurred.
T cells migrate to the epidermis, where they are called dendritic epidermal T cells.
microvet.arizona.edu /Courses/MIC419/Tutorials/Tcelldevelopment.html   (3818 words)

 T-cell Prolymphocytic Leukemia
Infiltration by lymphocytes in the bone marrow aspirates ranges from 30% to 100%, and the cell morphology is identical to that of the circulating blood cells.
T cell chronic lymphocytic leukemia with lymphocytes of unusual immunologic phenotype and function.
Expression of TIA-1 and TIA-2 in T cell malignancies and T cell lymphocytosis.
www.moffitt.org /moffittapps/ccj/v5n1/article2.html   (3295 words)

 Medical Dictionary: T cell - WrongDiagnosis.com
T cell: One type of white blood cell that attacks virus-infected cells, foreign cells, and cancer cells.
T cell (organ): T-cells or "T lymphocytes" are white blood cells that have a key purpose in the immune system called "cell-mediated immunity".
These cells identify and attack any body cells that are infected with viruses or otherwise identified as harmful or "non-self".
www.wrongdiagnosis.com /medical/t_cell.htm   (397 words)

 ScienceDaily: Scientists Create New Way To Study T Cell Signaling
T cell receptors (TCRs) are communicating with their corresponding signaling ligands on the membrane.
This signal must be enhanced and sustained long enough for the T cells to commit to mounting an immune response, and then must be cut off in time to avoid antigen-induced cell suicide or “apoptosis” of the T cells.
It has also been established that the control center for T cell signaling is at the junction or point of contact between T cells and antigens, dubbed the “immunological synapse” because it resembles the synapse between two communicating nerve cells.
www.sciencedaily.com /releases/2005/11/051117172309.htm   (1328 words)

 ScienceDaily: T Cell 'Brakes' Lost During Human Evolution
Siglec molecules seem to regulate T cell activation in chimpanzees by restricting the degree of signaling from the T cell receptor, which normally triggers the response of T cells in the immune system.
The study suggests that the expression of Siglecs on chimpanzee T cells in essence puts the brakes on the cells during chronic HIV infection, preventing progression to AIDS in chimpanzees.
The human volunteers could have experienced rapid activation of T cells and a resulting "cytokine storm." The research team asked for a sample of the anti-CD28 antibody from TeGenero in order to test it on chimpanzee blood, but the company declined their request.
www.sciencedaily.com /releases/2006/05/060502224533.htm   (1037 words)

 Skin Cancer - Cutaneous T Cell Lymphoma - DermatologyChannel
Cutaneous T cell lymphoma (CTCL) is a lymphoma of T cell (a type of white blood cell that is responsible for immune function) origin that affects the skin.
Cutaneous T cell lymphoma is frequently referred to as mycosis fungoides.
In this chronic disorder, malignant T cells migrate to, and multiply in, the skin.
www.dermatologychannel.net /skincancer/tcell.shtml   (1100 words)

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cells that kill cancer cells and cells infected with a virus.
When someone is infected with HIV for a long time, the number of CD4 cells they have (their CD4 cell count) goes down.
CD4 cell tests are normally reported as the number of cells in a cubic millimeter of blood, or mm3.
www.aids.org /factSheets/124-T-Cell-Tests.html   (798 words)

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