Thymus-derived lymphocytes

T lymphocytes, thymus-derived lymphocytes or T cells are formed in the thymus. They carry out immune reactions involving cell-cell interactions and are responsible for cell-mediated immunity. One distinguishes specific and non-specific cytotoxic killer T cells, (NK cells, natural killer cells), and helper T cells which cooperate with antigen-presenting cells, APC s, in the initiation of an immune response. Suppressor T cells dampen the action of helper T cells. 

T-Lymphocyte Thymus-derived cell of the immune system and agent of cellular immune responses. 

T-lymphocytes [thymus derived and posess characteristic surface receptors] and 5) macrophages [mononuclear phagocytic cells]. 

The thymus is a lympho-epithelial organ, located within the upper thorax. One of its fimctions is the conversion of certain lymphoid hematopoietic precursor cells originating from the bone marrow into thymus-derived lymphocytes (T-cells). 

Adenosine deaminase deficiency is associated with an immunodeficiency disease in which both thymus-derived lymphocytes (T cells) and bone marrow-derived lymphocytes (B cells) are sparse and dysfunctional. Purine nucleoside phosphorylase deficiency is associated with a severe deficiency of T cells but apparently normal B cell function. Immune dysfunctions appear to result from accumulation of dGTP and dATP, which inhibit ribonucleotide reductase and thereby deplete cells of DNA precursors. 

From 4 to 8 hours after the initial exposure to an allergen, a late-phase reaction may occur, which is thought to be due to cytokines released primarily by mast cells and thymus-derived helper lymphocytes. This inflammatory response likely is responsible for persistent, chronic symptoms including nasal congestion. 

SOD ha T cell Tc TcR TGA Th TLC TMP/SMX TNF Ts TX U V domain VLA Ml H m superoxide dismutase half-life thymus-derived lymphocyte cytotoxic T cell T-cell receptor thymine-guanine-adenine T helper cell thin layer chromatography trimethoprim/sulphamethazole tumour necrosis factor T suppressor cell thromboxane unit variable domain very-late antigen microlitre (10 6 litre) micrometre (10"6 metre)... 

Lymphocytes are derived from stem cells that differentiate within the primary lymphoid organs (bone marrow and thymus), where they mediate the immune... 

Thymus-derived, or T, lymphocytes also have an immunoglobulin-like surface receptor linked with accessory proteins to form the T-cell receptor (TCR). There are similarities between the BCR and TCR in that the recognition part of the T receptor complex is also a dimer. In most T cells, the dimer consists of a and [3 individual peptide... 

Leukocytes are derived from stem cells in the bone marrow. These cells become functionally mature cells granulocytes, lymphocytes, and macrophages. Lymphocytes divided into T cells (thymus derived) and B cells (bursa equivalent), depending on the site of maturation. 

Lymphocytes generally comprise between 25-30% of the white cells in human blood. These immunologically active cells are comprised of several classes, each of which has specific properties and functions. Lymphocytes are derived from stem cells located in the yolk sac and fetal Liver. Later, some stem cells originate from the bone marrow These cells then differentiate into lymphocytes in the primary lymphoid organs, principally the thymus and lymph nodes. 

For most antigens, the production of antibody (immunoglobulin) is based on the cooperative interaction of two types of lymphocyte, called T-cells (thymus-derived) and B-cells (bone marrow-derived). The T-cells, preprimed with macrophage-presented antigen, stimulate the B-cells to secrete copious quantities of antibody. However, on the basis of animal studies, such polysaccharide antigens as the type III pneumococcal polysaccharide have been considered to be T-cell-independent, as they are capable of triggering B-cells to produce antibody (IgM) in T-cell-deficient mice.167 These studies also indicated... 

A decline in immunologic function with increasing age has long been recognized. Thus, older individuals are more prone to various infectious diseases, autoimmune phenomena, amyloidosis, myelomatosis, chronic lymphoprolifera-tive disorders, and various forms of cancer. This decreased responsiveness of the immune system is primarily related to thymus-derived (T) lymphocytes (B17). However, B-lymphocytes are also affected since there is frequently a decreased... 

In this chapter we will review the development and function of lymphocytes, which include T cells (thymus derived), B cells (associated with antibody production) and natural killer (NK) cells (effectors of innate immunity). 

T-cells T (thymus derived) cell. These white blood cells, known as T lymphocytes, mature in the thymus and have regulatory immune funcdons. As part of the adapdve (cell-mediated) immune system, these cells can recognize andgens processed by andgen-presendng cells in the context of specific receptors. The cell surface protein CDS is a marker for these cells. 

Another set of antigenic markers associated with the same chromosome as the MHC in the mouse recognizes certain lymphocyte surface receptors (Ly antigens) and has been used to differentiate thymus-derived lymphocytes (T lymphocytes) involved in helper and suppressor functions (Cantor and Boyse, 1975). 

Glucocorticoids depress monocyte/macrophage fund ion and decrease circulating thymus-derived lymphocytes (T-cclis), especially helper Tj lymphocyte.s. The release of interleukins lL-1 and lL-2 (necessaty to activate and. stimulate iymphantigenic stimulation and the prrxluc-vion of antibody are also inhibited. 

Tanabe S, Lu Z, Luo Y, Quackenbush El, Berman MA, Colbns-Racie LA, Mi S, Reilly C, Lo D, Jacobs K, Dorf ME. Identification of a new mouse P-chemokine, thymus-derived chemotactic agent 4, with activity on T lymphocytes and mesangial cells. I Immunol 1997 159 5671-5679. 

Immunologically reactive or immunocompetent cells are lymphocytes which, together with granulocytes and erythrocytes, originate from common hemopoietic stem cells (Wu et al. 1967). The sites of primary lymphopoiesis are the bursa of Fabricius (in birds) and the thymus in mammals no bursa has been found but an equivalent organ is inferred (Mitchell and Miller 1968 Perey et al. 1968 Owen and Ritter 1969). Lymphocytes which differentiate within the thymus independent of antigenic influence become thymus-derived or thymus-processed lymphocytes, so-called T-cells. It is now generally accepted that a cooperation between T-cells and bursa-equivalent lymphocytes (B-cells) is necessary for induction of IgM... 

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