activated lymphocyte

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activated lymphocyte

A lymphocyte stimulated by exposure to a specific antigen or by macrophage processing so that it is capable of responding to a foreign antigen by neutralizing or eliminating it.
See also: lymphocyte


a mononuclear, nongranular leukocyte having a deeply staining nucleus containing dense chromatin and a sparse, pale-blue-staining cytoplasm. It participates in immunity.

activated lymphocyte
one that has reacted on exposure to antigen or to a mitogen.
lymphocyte-activating antigen
see lymphocyte-defined antigen (below).
B l's
thymus-independent lymphocytes, which develop from stem cells in hematopoietic tissue, including the blood islands of the fetal yolk sac, the fetal liver and spleen, and the bone marrow. The B in B lymphocyte refers to the bursa of Fabricius, an organ in birds where B cell differentiation occurs. No analogous organ has been found in mammals, though an equivalent is assumed to exist—probably bone marrow.
B lymphocytes are involved in humoral immunity, i.e. the production of antibodies. A small, mature B lymphocyte can be activated by the binding of an antigen to specific cell-surface receptors. This induces proliferation of the cell, resulting in an expanded clone of cells specific for that antigen. These cells can then differentiate and begin to secrete immunoglobulin (Ig) molecules. Antibody production for most antigens involves interaction with helper T lymphocytes. All of the cells of a single clone secrete Ig that binds specifically to the antigen that stimulated the production of antibody. Mature antibody-secreting cells are plasma cells. Following blastogenesis some of the cells produced by division revert to small lymphocytes and remain as a longlived clone of 'memory' cells.
lymphocyte blastogenesis
increased DNA synthesis followed by cell division and differentiation of lymphocytes in response to antigens or mitogens; an in vitro test of lymphocyte function.
lymphocyte-defined antigen
histocompatibility antigens found on lymphocytes, macrophages, epidermal cells and sperm, capable of stimulating division in allogeneic lymphocytes. Called also lymphocyte-activating antigen.
helper l's
a subset of T lymphocytes that is itself comprised of Th1 and Th2 cells that cooperate with and regulate B lymphocytes in the antibody response and with themselves and other effector T lymphocytes.
histiocytic lymphocyte
intraepidermal l's
cellular components of the cutaneous immune system.
intraepithelial l's
cellular components of the mucosal immune system.
large lymphocyte
large granular lymphocyte
see natural killer cell.
memory lymphocyte
see memory cell.
natural killer (NK) lymphocyte
see natural killer cell.
non-T, non-B lymphocyte
see null cell.
pre-B lymphocyte
a progenitor B cell derived from bone marrow stem cells.
resting lymphocyte
small lymphocytes in the G0 stage of the cell cycle, prior to activation.
small lymphocyte
unstimulated B and T lymphocytes.
lymphocyte stimulation test
see lymphocyte blastogenesis (above).
suppressor (Ts) lymphocyte
see T lymphocytes (below).
T l's
lymphocytes produced from pluripotential bone marrow stem cells which migrate during late embryogenesis to the thymus. Enormous numbers of cells are produced in the thymus, most of which are destroyed there. Less than 10% of cells which are non-self reactive leave the thymus to populate the T lymphocyte areas of the secondary lymphoid tissues (lymph nodes, spleen, Peyer's patches, etc.). At least four subsets of T lymphocytes are defined by cell surface markers and more especially by function.
Three of the subsets are regulatory cells called T helper (Th) 1 and 2, and T suppressor (Ts) lymphocytes. The other subset is an effector cell called cytotoxic T (Tc) lymphocytes or CTLs. Following antigen binding to antigen-specific T cell receptor (TCR) molecules, T lymphocytes, like B lymphocytes, undergo blastogenesis, in which they enlarge and divide. Some daughter cells revert to form an expanded clone of memory T lymphocytes. For both regulatory and effector functions, T lymphocytes produce a number of substances generally referred to as lymphokines. Lymphokines, unlike antibody, do not bind specifically with antigen, but rather they direct cell functions.
thymus-derived lymphocyte
see T lymphocytes (above).
lymphocyte transfer test
injection of lymphocytes from a potential graft recipient into the skin of a potential donor can be a test of histocompatibility, primarily in humans at the LD loci. Noncompatibility is marked by an inflammatory skin reaction.
lymphocyte transformation test
see lymphocyte blastogenesis (above).
lymphocyte transforming factor (LTF)
an obsolete term for a lymphokine that causes transformation and clonal expansion of nonsensitized lymphocytes.
tumor-infiltrating l's (TILs)
T lymphocyte preparations from surgically removed cancer tissue that may be activated in vitro and returned to the host as a basis for specific anticancer therapy.
References in periodicals archive ?
15] This suggests that LUCs represent virally activated lymphocytes, consistent with our hypothesis that circulating LUCs would be present in higher numbers in individuals with chronic immune stimulation.
Lycera's bioenergetics program is focused on developing orally available small molecules that exploit bioenergetic abnormalities in pathologically activated lymphocytes and result in the selective silencing of these cells, while keeping healthy immune cells intact.
Fine-needle aspiration of the lymph node showed necrosis and mature, activated lymphocytes.
But investigators at the University of Alberta, Edmonton, discarded the standard islet-toxic immunosuppressive regimen routinely used in whole-organ transplants in favor of a gentler sirolimus- and tacrolimus-based, corticosteroid-free regimen utilizing daclizumab, a monoclonal antibody directed against the interleukin-2 receptor on activated lymphocytes.
In contrast, activated lymphocytes contain mainly IMPDH-II (20-22), which is four times more sensitive to MPA than IMPDH-I (23).
MDX-1106/ONO-4538 is a novel fully human antibody designed to target and inhibit the function of PD-1 (programmed cell death 1), a receptor expressed on the surface of activated lymphocytes (T-cells).
MDX-1401 is a fully human, non-fucosylated antibody that targets CD30, a marker for activated lymphocytes that is present on malignant cells of HL as well as other CD30-expressing cancers.
Finding Mollaret-like cells admixed with activated lymphocytes may be a useful, readily-available test that provides supportive evidence of viral encephalitis in the appropriate clinical setting, until more definitive tests are available.
CD70 is an ideal target for antibody-based therapy because it is expressed on activated lymphocytes and dendritic cells, but is absent on those cells when in a resting state," said Jonathan Drachman, Vice President, Early Clinical Development at Seattle Genetics.

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