Λεξικό .. Cytokines

Cytokines are soluble factors that are critical for the pathophysiology of the immune system and exhibit other important functions Cytokines represent a group of proteins that are synthesized and secreted by any nucleated cell, that bind to specific receptors on target cells, and that regulate the activity, proliferation and differentiation of immune as well as nonimmune cells. They are glycoproteins with a molecular weight of 15000 to 20000 daltons. These proteins often are involved in the pathophysiology of human disease, and also have a potential therapeutic role in these same diseases.

Cytokines produced by type 1 helper T (Th1) lymphocytes, such as interferon (IFN)-g, play a pathogenic role in proliferative glomerulonephrites (GN), as well as in the acute rejection of kidney allografts. Cytokines produced by type 2 Th (Th2) lymphocytes, such as interleukin (IL)-4, IL-5, and IL-13), predominate in membranous GN and in minimal change disease. Although these proteins have been variously called lymphokines, monokines, interleukines (IL), interferons (IFN), and growth factors, it has become apparent that such terminology is inadequate, as the range of biological activities of these proteins is too broad and overlapping for terms of classification to be simply based upon a presumed cellular source or presumed principal physiological effect.

There is also a strong relation between cytokines and other mediators such eicosanoids and hormones (See Interleukin, -es, lymphokines, interferons). There is clear evidence epidermal cells, including keratinocytes, Langerhans cells and melanocytes, upon stimulation are able to produce cytokines such as multifunctional inflammatory mediators (IL-1, IL-6, IL-8, TN Fa), colony-stimulating factors, growth factors and recently identified suppressor factors. Cytokines usually have multiple overlapping activities. Interacting cytokines need a proper balance.

Excessive or insufficient production of these mediators may contribute to local and systemic inflammatory disease states. Cytokines include the Interleukines (IL1-18) Hematopoietic growth factors (Epo, CSF), Interferones (IFN), Tumor necrosis factors (TNF,), Growth factors (EGF, TGF, FGF, PDGF), Inhibitors (IL 1 ra...). During the early-phase allergic reaction, mast cells release histamine and other preformed elements such as enzymes, hydrolases, and proteoglycans, and also release proinflammatory mediators such as prostaglandins (e.g. PGD2), leukotrienes, platelet-activating factor, bradykinin, and cytokines (e.g. tumour necrosis factor-α and interleukins IL-4, IL-5, IL-6, IL-10, and IL-13).. Proinflammatory mediators initiate a complex network of inflammatory phenomena involving adhesion molecules, Th2 T lymphocytes (which mainly release IL-4, IL-5, and IL-13), cytokines, and mediators. These result in the late and ongoing allergic symptoms of nasal congestion, asthma, and urticaria (Bousquet et al 2001).

References

Bousquet J, Van Cauwenberge P, Khaltaev N. Allergic rhinitis and its impact on asthma. J Allergy Clin Immunol 2001;108(Suppl. 5):S147-S334.

Coulon, P.: Cytokines in regulation of the immune response. In Conversations in Allergy. Fort-de-France, Martinique, France. March 5-10, 1988. The UCB Institute of Allergy.Luger, T.A.: The cytokine network. Allergologie (1991) 14, No. 5, p. 185-188.

Lazzeri E, et al: Cytokines and chemokines in nephropathies and renal transplant G Ital Nefrol 2002 Nov-Dec;19(6):641-9

Luger, T.A.: Role of Epidermal Cytokines in the Pathogenesis of Inflammatory Skin Diseases.  In Highlights in Allergy and Clinical Immunology ed:  by B. Wüthrich. Hogrefe and Huber Publ., p. 223, 1992.

Merrimal, C.R., et al: Comparison of leukocyte pyrogen and leykocytic endogenous mediators. proc. Soc. Biol. Med. 1977; 154:224.Mandrup-Poulsen, T. et al: Cytokines cause functional and structural damage to isolated islets of langerhans. Allergy 40, No. 6, p. 424. 1985.