Cytokines are soluble peptides that induce activation, proliferation and differentiation of cells of the immune system. Moreover, cytokines influence functions of cells of other tissues and organs, esp. of nervous and endocrine systems. They act in very low concentrations (10-10 M) what makes them to be like hormones. However, hormones tend to be produced constitutively and are produced by endocrine organs. Cytokines, on the contrary, are secreted after activation of particular cells and secretion is short-lived, generally ranging from a few hours to a few days and there are no specialised organs for their synthesis. Cytokines influence target cell in 4 different ways, synergistic, antagonistic, pleiotropic, and redundant way, respectively. They ca act in a autocrine, paracrine and endocrine manner. There are many cytokines that can be divided into those regulating innate and adaptive immunity, to the group of cytokines endowed by chemotactic properties and those supporting growth of hematopoietic and immune system cells.
Adaptive immunity recognises an infinite variety of antigens by millions of cell-surface receptors. Instead, the innate immune system recognition of antigens is based on a much smaller number of receptors. They recognise conserved molecules of microbes (that are absolutely vital for their life, germs cannot survive without them. Moreover, they are not present in cells of their hosts. The term “Pathogen associated molecular patterns (PAMPs”) was coined for them and receptors recognising them are called “Pattern recognition receptors (PRRs).“ There are 4 basic families of PRRs: TLR, NLR, CLR, and RHL. Recognition of their specific ligand induces signaling pathways that results in activation of inflammatory processes and mechanisms of specific immunity. The immune system has to recognise not only a danger resulting from germs, however also that resulting from a breakdown of homoeostasis from internal disturbances in our body. The molecules indicating such disturbances are known under the term “Danger (damage) associated molecular patterns (PAMPs”).
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citation: Milan Buc: Cytokines. PAMPs and PRRs. Multimedia support in the education of clinical and health care disciplines :: Portal of Faculty of Medicine, Comenius University [online] , [cit. 09. 12. 2021]. Available from WWW: https://portal.fmed.uniba.sk/articles.php?aid=181. ISSN 1337-9577.