Activated T lymphocytes

Although this may suffice, additional factors contribute to this process. Activated T-lymphocytes secrete amongst other cytokines also interferon y which... 

The chimeric human/murine (basiliximab and dacluzi-mab) or murine (inolimomab) monoclonal antibodies are specifically directed against a part (CD25) of the interleukin-2 (IL-2) receptor. Binding of one of these antibodies to CD25 thereby displaces physiological IL-2 and prevents proliferation of activated T-lymphocytes. 

IL-1 Macrophages, monocytes, endothelial cells, B lymphocytes, activated T lymphocytes Stimulates fibroblasts and chondrocytes to release matrix metalloproteinases... 

IL-6 T lymphocytes, monocytes, macrophages, synovial fibroblasts Activates T lymphocytes, induces acute-phase response, stimulates growth and differentiation of hematopoietic precursor cells stimulates synovial fibroblasts... 

Loetscher M, Gerber B, Loetscher P, et al. Chemokine receptor specific for IP10 and mig structure, function, and expression in activated T-lymphocytes. J Exp Med 1996 184(3) 963-969. 

Kelly, ME, Clay, MA, Mistry, MJ, Hsieh-Li, HM, and Harmony, JA, 1994. Apolipoprotein E inhibition of proliferation of mitogen-activated T lymphocytes Production of interleukin 2 with reduced biological activity. Cell Immunol 159, 124—139. 

Bhattacharyya, S.P., Drucker, I., Reshef, T., Kirshenbaum, A.S., Metcalfe, D.D. and Mekori, Y.A. (1998) Activated T lymphocytes induce degranulation and cytokine production by human mast cells following cell-to-cell contact. Journal of Leukocyte Biology 63, 337-341. 

It plays a role in activating B-lymphocytes, along with additional cytokines, and may also play a role in activating T-lymphocytes. 

Bentley, A.M. et al., Activated T-lymphocytes and eosinophils in the bronchial mucosa in isocyanate-induced asthma, J. Allergy Clin Immunol., 89, 821, 1992. 

Caspar-Bauguil, S., Tkaczuk, J., Haure, M.J., Durand, M., Alcouffe, J., Thomsen, M., Salvayre, R., and Benoist, H., 1999, Mildly oxidized low-density lipoproteins decrease early production ofinterleukin 2 and nuclear factor kappaB binding to DNA in activated T-lymphocytes, Biocfem. J. 337 269-274. 

Microorganism Activate T Lymphocytes and Bystander Cells in the Skin in Atopic Dermatitis An important strategy by which S. aureus exacerbates atopic dermatitis is by secreting exotoxins. Some of them function as superantigens, which stimulate activation of T cells and major histocompatibility (MHC) class II + APC or keratinocytes, which express MHC class II upon activation. Many effects on T lymphocytes and other cells are elicited by superantigens (table 1). 

The biological activities of several other interleukins also render them likely candidates for therapeutic application. IL-5 represents one such candidate. IL-5 is a 115 amino acid glycoprotein produced mainly by activated T lymphocytes and also by mast cells. It functions as a homodimer, exhibiting a molecular mass of 45 kDa. The individual polypeptide chains interact non-covalently and the overall dimeric structure is stabilized by two interchain disulphide linkages between cysteines 42 and 84 of each chain. Removal or alterations of the cytokine s carbohydrate side-chain does not appear to affect its biological activity. 

Basiliximab is a chimeric mouse-human monoclonal antibody to the IL-2Ra receptor of T cells and daclizumab (Zenapax) is a humanized monoclonal antibody against the same receptor. They prevent binding of interleukin-2 to the CD25 antigen on activated T-lymphocytes thus inhibiting T-lymphocyte proliferation. Like the similar drug basiliximab, daclizumab reduces the incidence and severity of acute rejection in kidney transplantation without increasing the incidence of opportunistic infections. 

Clinical pharmacology Basiliximab is a chimeric (mouse/human) interleukin-2 receptor antagonist. It is directed against the interleukin-2 receptor-alpha chain (CD25) on activated T-lymphocytes, and is a potent inhibitor of interleukin-2-mediated activation of lymphocytes, a critical pathway in the cellular immune response involved in allograft rejection. Another anti-CD25 monoclonal antibody, dacUzumab (Zenapax), has the same indication as basiliximab. 

Interferons are proteins that are currently grouped into three families IFN- , IFN-B, and IFN-7. The IFN- and IFN-B families comprise type I IFNs, ie, acid-stable proteins that act on the same receptor on target cells. IFN-7, a type II IFN, is acid-labile and acts on a separate receptor on target cells. Type I IFNs are usually induced by virus infections, with leukocytes producing IFN- . Fibroblasts and epithelial cells produce IFN-B. IFN-7 is usually the product of activated T lymphocytes. 

The principal mechanism of action is inhibition of dihydrofolate reductase, an enzyme important in the production of thymidine and purines. At the high doses used for chemotherapy, methotrexate inhibits cellular proliferation. However, at the low doses used in the treatment of inflammatory bowel disease (12-25 mg/wk), the antiproliferative effects may not be evident. Methotrexate may interfere with the inflammatory actions of interleukin-1. It may also stimulate increased release of adenosine, an endogenous anti-inflammatory autacoid. Methotrexate may also stimulate apoptosis and death of activated T lymphocytes. 

Class Immunosuppressive chimeric monoclonal antibody, specifically binds to and blocks the interleukin-2 receptor alpha chain on the surface of activated T- lymphocytes... 

Interleukin-2 (T-cell growth factor Fig. 30-6A) is secreted by some activated T-lymphocytes. This 133-residue largely helical protein is involved in generation of cytotoxic T-cells, stimulation of interferon release, and of release of a B-cell growth factor.269 Considerable excitement has accompanied the possibility of activating lymphocytes with IL-2 produced from cloned genes in bacteria to increase their ability to kill cancer cells. However, IL-2 is toxic, and this is limiting its use. See also Chapter 31, Section C. 

IFN-y modulates a number of components of the immune response. This is the only type II IFN whereas there are more than 20 types of type I IFNs (IFN-a, IFN-(3, IFN-w and IFN-t). It is not related to type I IFNs, has separate receptors and is encoded by a different chromosomal locus. IFN-y is produced by activated T lymphocytes (THi and CD8+ cells), NK cells, B cells, NKT cells and professional APCs. It promotes the activity of cytolytic T lymphocytes, macrophages and NK cells. The cell self-activation and activation of nearby cells in part may result from IFN-y production by professional APCs, which include monocyte/macrophage and dendritic cells. The early host defense against infection is likely to utilize IFN-y secreted by NK and professional APCs. In acquired immune responses, T lymphocytes are the major source of IFN-y. 

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