Cytokine types

Elson, G. C., Graber, P., Losberger, C., Herren, S., Gretener, D., Menoud, L. N., Wells, T. N., Kosco-Vilbois, M. H., and Gauchat, J. F. (1998). Cytokine-like factor-1, a novel soluble protein, shares homology with members of the cytokine type I receptor family. / Immunol. 161, 1371-1379. 

Nerve growth factor (NGF) Cystine knot motif Promotes cell death in the nervous system, when bound to p75l t Two types of receptor, co-receptor NGFR-a,P p75NGFR, have no tyrosine kinase activity. They are cytokine-type receptors like the TNF-receptor... 

Another subdivision of type IV hypersensitivity reactions has categories distinguished by the effector cells and mediators involved together with the resulting associated cutaneous reactions. Four subdivisions are defined type IVa, mediated by monocytes with IFN-y as dominant cytokine type IVb, mediated by eosinophils with IL-5 and IL-4 involvement type IVc, mediated by T cells with perforin and granzyme B as important effector molecules and type IVd, mediated by neutrophils with IL-8 involvement. Representative skin reactions for the so-called types IVa, b, c, and d are, respectively, maculopapular rash, maculopapular rash with eosinophilia, Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). 

Glucocorticoids have been shown to inhibit gene transcription of other proteins involved in the inflammatory process, including the key inflammation mediators called cytokines (IL-1, IL3—6, IL8, GM-CSF, TNFa) (10,58,63—65). Steroids have been also shown to suppress the formation of cytokine receptors (10) dexamethasone, in particular, downregulates gene transcription of angiotensin II type 2 receptors (66). 

Interferons [alFN, piFN and ylFN]. Interferons are a family of glycosylated proteins and are cytokines which are produced a few hours after cells have been infected with a virus. Interferons protect cells from viral infections and have antiviral activities at very low concentrations ( 3 x 10 M, less than 50 molecules are apparently sufficient to protect a single cell). Double stranded RNA are very efficient inducers of IFNs. There are three main types of IFNs. The aIFNs are synthesised in lymphocytes and the piFNs are formed in infected fibroblasts. The a and P families are fairly similar consisting of ca 166 to 169 amino acids. Although ylFNs are also small glycosylated proteins (ca 146 amino acids), they are different because they are not synthesised after viral infections but are produced by lymphocytes when stimulated by mitogens (agents that induced cell division). 

In type III or immunocomplex-mediated allergy, IgG antibodies form complexes with antigen. At low exposures, the body is able to remove diese complexes, but if there is a severe exposure, immunocomplexes release a variety of proinflammatory cytokines. The involvement of this mechanism is clearest in serum sickness. This mechanism is also considered to be most important in the development of extrinsic allergic alveolitis (hypersensitivity pneumonitis, especially... 

Antigens commonly induce the activation of T-lymphocytes of the T helper type (Th). In the case of Type IV b reactions the predominant responding cell is the Th-1 subtype. By secreting many cytokines, including... 

A mode of action of a molecular messenger such as a cytokine or hormone in which the molecule binds to receptors on, and affects the function of, the cell type that produced it. 

IFN- 3 reduces the induction by inflammatory cytokines of adhesion molecules and of MHC class I and II complex on endothelial cells, a process preceding attachment and transendothelial migration of T-cells. These anti-inflammatory effects of IFN- 3 exemplify antagonistic actions of type I and type IIIFN. There is, indeed, much clinical evidence for the involvement of IFN-y in inflammatory processes - through activation of iNOS and subsequent secretion of NO - leading to the establishment of autoimmune diseases as for instance in rheumatoid arthritis. 

The key end result of TLR signalling is the induction of cytokines. Cytokines are proteins produced during an immune response that allow the maturation, activation and differentiation of effector cells in the immune system. The activation of NFkB and AP-1 by the MyD88 and the TREF dependent pathways leads to the production of proinflammatory cytokines such as IL-6, TNF-a and various chemokines. This pathway can also activate IRF-7 via TLR-7and TLR-9 allowing Type-I interferons to be produced. 

TNF is a pleiotropic cytokine exerting a wide range of cellular responses, that affect biological processes such as lipid metabolism, coagulation, and insulin resistance and the function of endothelial cells. As a major proinflammatory cytokine TNF is also involved in progression of diseases like cancer, Alzheimer, Diabetes type II, cardiovascular, pulmonary or neurological disorders, and many autoimmune diseases. Blocking the action of TNF clearly reduces its inflammatory potential on various autoimmune disorders like Crohn s disease, rheumatoid arthritis (RA), and psoriasis. 

Type I allergic reactions are inappropriate immune responses to an allergen with preferential synthesis of immunoglobulin E (IgE), a special antibody class, which binds to mast cells and basophilic granulocytes via Fee receptors. Binding of the allergen to the cell-bound IgE initiates the rapid release of allergic mediators, most prominently histamine, and the de novo synthesis of arachidonic acid metabolites and cytokines, which are responsible for the clinical symptoms. 

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