<\/b>The cytokine family<\/b><\/strong><\/p>\n

Cytokines are an important group of proteins realizing intercellular communications among cells\u00a0of the same tissue (paracrine) or of different tissues\u00a0(endocrine). Such communications are\u00a0essential for the correct synchronized\u00a0reactions of the cells of different tissues. In the literature\u00a0different designations are used to denote these factors: lymphokines, monokines, interleukins,\u00a0and growth factors, which are now unified under the common name cytokines<\/i><\/em>. The main cytokines include interleukins 1 to 18 (IL-1 to IL-18); interferons \u03b1, \u03b2, and \u03b3 (IFN\u03b1, IFN\u03b2, and IFN\u03b3, respectively); tumor necrosis factors\u03b1 and \u03b2 (TNF\u03b1 and TNF\u03b2); colony-stimulating factors \u2014 granulocyte, macrophage, and granulocyte-macrophage (CSF-G, CSF-M, CSF-GM, respectively); basic and acid fibroblast growth factors (aFGF and bFGF); and\u00a0others.<\/p>\n

There are two types of human interferons, type I and type II, and interferon-like cytokines. Type I human interferons consist of six classes:\u00a0IFN-\u03b1, IFN-\u03b2, IFN-\u03b5, IFN-\u03ba, IFN-\u03c9, and IFN-\u03bd. However, a large\u00a0number of type I interferons are found in other animal species. Type II interferon consists only of IFN-\u03b3. In addition, three related human interferon-like cytokines have been reported: IL-28A,\u00a0IL-28B, and IL-29. There\u00a0is only one IFN-\u03b2, IFN-\u03b5, IFN-\u03ba, IFN-\u03c9, and IFN-\u03bd, but the IFN-\u03b1 proteins\u00a0consist of twelve individual proteins.<\/p>\n

Differences between IFN\u03b3 and IFN\u03b1\/\u03b2<\/b><\/strong><\/p>\n

The main differences between IFN\u03b3 (type II) and IFN\u03b1\/\u03b2 (type I) are summarized as follows:<\/p>\n

\n
• Different primary structure.<\/li>\n
• The IFN\u03b1\/\u03b2 genes are not split, whereas the IFN\u03b3 gene has introns.<\/li>\n
• IFN\u03b1\/\u03b2 share a common receptor that is different from that of IFN\u03b3.<\/li>\n
• The two types of interferons induce or suppress the synthesis ofdifferent proteins.<\/li>\n
• IFN\u03b1\/\u03b2 stimulate mainly the activity of the natural killer (NK) cells,whereas IFN\u03b3 stimulates mainly the macrophages.<\/li>\n
• IFN\u03b1\/\u03b2 are stable at pH 2.0; IFN\u03b3 is acid labile.<\/li>\n
• Differences are in the signaling pathway leading to the correspondingactivity.<\/li>\n<\/ul>\n

  The different receptors and the differences in the metabolic signaling\u00a0pathways open avenues for a\u00a0combined clinical use of IFN\u03b3 and IFN\u03b2 or IFN\u03b3 and IFN\u03b1. In the latter case, the possible effect\u00a0of IFN\u03b3 on the IFN\u03b1 receptor has\u00a0to be taken into consideration. This effect seems to depend on\u00a0the cellular\u00a0type. In the neuroblastoma cell line T98G, IFN\u03b3 suppresses the binding of\u00a0IFN\u03b1 to its receptor, possibly by affecting its dissociation constant (Kd). In other tumor cell lines (melanoma HMV-1, kidney\u00a0carcinoma ACHN, Daudi lymphoma), IFN\u03b3 induces the receptors of IFN\u03b1\u00a0but only under the condition that IFN\u03b3 preceded the treatment with IFN\u03b1.<\/p>\n

  The Principal Properties of Interferon<\/b><\/strong><\/p>\n

  Interferon possesses certain characteristic properties which\u00a0distinguish it from other virus inhibitors. These include:<\/p>\n

  \n
  1. Tissue and species specificity.<\/li>\n
  2. Insensitivity to the action of virus-neutralizing antibodies.<\/li>\n
  3. Resistance to the action of an acid medium and thermostability at 56\u00b0C.<\/li>\n
  4. Sensitivity to proteolytic enzymes.<\/li>\n
  5. Ability to inhibit reproduction of certain viruses in tissuecultures, i.e., absence of virus specificity.<\/li>\n<\/ol>\n

     Besides these properties, interferon also possesses others\u00a0which characterize it as a protein of low\u00a0molecular weight with\u00a0particular physicochemical properties. Details of the various\u00a0properties of interferon are given below.<\/p>\n

     Physicochemical Properties<\/b><\/strong><\/p>\n

     Interferon is a protein of low molecular weight. Its molecule\u00a0contains the following components:\u00a0tyrosine 2.3%, tryptophan 2.6%,\u00a0arginine 7.2%, lysine 11.1%. It does not contain nucleic acids and\u00a0only traces of carbohydrate are present.\u00a0Interferon has a slightly acid reaction and contains disulfide bridges. The number of polypeptide chains has not been established. However, the reaction of this protein is alkaline and the isoelectric point is close to pH 6.9-7.1 or 7.2-7.8.<\/p>\n

     Species Specificity<\/b><\/strong><\/p>\n

     One of the most important properties of interferon is its\u00a0well-marked species specificity. This property of interferon was\u00a0first described by Tyrrell. In his experiments the inhibitors\u00a0obtained in the chorioallantoic membranes of the chick embryo and\u00a0in cultures of calf kidney cells possessed antiviral activity only\u00a0in homologous cells. Isaacs and Westwood also showed that\u00a0vaccinal lesions in the rabbit’s skin were actively inhibited by interferon produced in cultures of rabbit cells,\u00a0whereas chick interferon gave a very weak effect in such cases. The opposite effect\u00a0was obtained in experiments on chick embryos, i.e., only chick and\u00a0not rabbit interferon was active. Later the\u00a0marked species specificity of interferon was confirmed by most investigations.<\/p>\n

     Antigenic Properties<\/b><\/strong><\/p>\n

     The weakness of the antigenic properties of interferon is\u00a0confirmed by the results obtained by Falcoff and co-workers,\u00a0who found that repeated intravenous injections of human leukocytic\u00a0interferon into adults and children were not accompanied by the\u00a0formation of any detectable\u00a0quantities of antibodies. No antibodies\u00a0could be detected even in a child aged 6 years who\u00a0received 3620 ml\u00a0of leukocytic interferon intravenously over a period of 400 days.<\/p>\n

     References:<\/h4>\n

     Solov’ev, V. (2012). Interferon: Theory and Applications. Springer Science & Business Media.<\/p>\n

     Tsanev, R. G., & Ivanov, I. (2001). Immune interferon: properties and clinical applications. CRC Press.<\/p>\n","protected":false},"excerpt":{"rendered":"

     The cytokine family Cytokines are an important group of proteins realizing intercellular communications among cells\u00a0of the same tissue (paracrine) or of different tissues\u00a0(endocrine). Such communications are\u00a0essential for the correct synchronized\u00a0reactions …<\/p>\n","protected":false},"author":1,"featured_media":500,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[127],"tags":[129,128],"_links":{"self":[{"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/posts\/499"}],"collection":[{"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/comments?post=499"}],"version-history":[{"count":1,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/posts\/499\/revisions"}],"predecessor-version":[{"id":501,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/posts\/499\/revisions\/501"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/media\/500"}],"wp:attachment":[{"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/media?parent=499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/categories?post=499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.creative-peptides.com\/blog\/wp-json\/wp\/v2\/tags?post=499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}