| t4 helper lymphocyte | A specific type of lymphocyte, derived from the thymus gland, that plays an important role in cellular immunity. T4 lymphocytes (CD4 cells) are decreased (absolute counts less than 200) in patients with AIDS resulting in compromised immune function. (27 Sep 1997) |
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| thymus derived lymphocyte | <haematology, immunology> A class of lymphocytes, so called because they are derived from the thymus and have been through thymic processing. Involved primarily in controlling cell-mediated immune reactions and in the control of B-cell development. The T-cells coordinate the immune system by secreting lymphokine hormones. There are 3 fundamentally different types of t cells : helper, killer, and suppressor. Each has many subdivisions. T-cells are also called t lymphocytes. They bear T-cell antigen receptors (CD3) and lack Fc or C3b receptors. Major T-cell subsets are CD4 (mainly helper cells) and CD8 (mostly cytotoxic or suppressor T-cells). Uncontrolled proliferation of this type of cell gives rise to T-cell leukaemia/lymphoma. (21 Jun 1999) |
| T lymphocyte | <haematology, immunology> A class of lymphocytes, so called because they are derived from the thymus and have been through thymic processing. Involved primarily in controlling cell-mediated immune reactions and in the control of B-cell development, aiding B lymphocytes in making antibodies, and helping in the recognition and rejection of foreign tissues. T lymphocytes are also important in the bodys defense against cancer. They bear T-cell antigen receptors (CD3) and lack Fc or C3b receptors. Major T-cell subsets are CD4 (mainly helper cells) and CD8 (mostly cytotoxic or suppressor T-cells). Uncontrolled proliferation of this type of cell gives rise to T-cell leukaemia/lymphoma. (13 Nov 1997) |
| t-lymphocyte | A white blood cell made in the thymus gland, a lymphoid structure in the upper chest. T lymphocytes are also called T-cells. (the t in T-cell stands for thymus). These cells coordinate the immune system by secreting lymphokine hormones. There are 3 fundamentally different types of t lymphocytes : helper, killer, and suppressor. (12 Dec 1998) |
| t-lymphocyte subsets | A classification of T-lymphocytes, especially into helper/inducer, suppressor/effector, and cytotoxic subsets, based on structurally or functionally different populations of cells. (12 Dec 1998) |
| transformed lymphocyte | See: lymphocyte transformation. (05 Mar 2000) |
| epitopes, b-lymphocyte | Antigenic determinants recognised and bound by the B-cell receptor. Epitopes recognised by the B-cell receptor are located on the surface of the antigen. (12 Dec 1998) |
| epitopes, t-lymphocyte | Antigenic determinants recognised and bound by the T-cell receptor. Epitopes recognised by the T-cell receptor are often located in the inner, unexposed side of the antigen, and become accessible to the T-cell receptors after proteolytic processing of the antigen. (12 Dec 1998) |
| tumour-infiltrating lymphocyte | <haematology, oncology> Special cancer-fighting cells of the immune system found in tumours. In a type of experimental therapy, scientists harvest these cells from the tumour, grow them in a laboratory and then return them to the patient with the hope of the cells destroying the tumour. These cells can be collected from the site of a tumour and exposed to IL-2 in vitro. When these cells are injected back into the tumour bearing host, they will specifically kill the tumour from which they originated. (05 Mar 2000) |
| lymphocyte | <haematology> White cell of the blood that are derived from stem cells of the lymphoid series. Two main classes are recognised, T and B lymphocytes, the latter responsible (when activated) for production of antibody, the former subdivided into subsets (helper, suppressor, cytotoxic T-cells) and responsible both for cell-mediated immunity and for stimulating B-cells. (18 Nov 1997) |
| lymphocyte activation | <haematology> The change in morphology and behaviour of lymphocytes exposed to a mitogen or to an antigen to which they have been primed. The result is the production of lymphoblasts, cells that are actively engaged in protein synthesis and that divide to form effector populations. Should not be confused with transformation of the type associated with oncogenic viruses and activation is therefore perhaps a better term. (18 Nov 1997) |
| lymphocyte cooperation | T-cell enhancement of the B-cell response to thymic-dependent antigens. (12 Dec 1998) |
| lymphocyte count | A count of the number of lymphocytes in the blood. (12 Dec 1998) |
| lymphocyte depletion | Immunosuppression by reduction of circulating lymphocytes or by T-cell depletion of bone marrow. The former may be accomplished in vivo by thoracic duct drainage or administration of antilymphocyte serum. The latter is performed ex vivo on bone marrow before its transplantation. (12 Dec 1998) |
| lymphocyte function associated antigen | A member of the integrin family that is expressed on all leukocytes and binds to ICAM-1 and ICAM-2 on a variety of cells. (05 Mar 2000) |