Microbiology Cytokines PDF

Microbiology Immunology Cytokines Microbiology| Cytokines Contents : Cytokines 3 Chemokines 11 Interferons 12 Interleukins 15 Microbiology| Cytokines Cytokines are low molecular weight (30KDa) regulatory protein or glycoprotein secreted by White blood cells and various other cells in body in respons...

Microbiology Immunology Cytokines Microbiology| Cytokines Contents : Cytokines 3 Chemokines 11 Interferons 12 Interleukins 15 Microbiology| Cytokines Cytokines are low molecular weight (30KDa) regulatory protein or glycoprotein secreted by White blood cells and various other cells in body in response to number of stimuli. These regulatory proteins help in regulating the development of immune effector cells and some cytokines also have their own functions. Microbiology| Cytokines Properties of cytokines : 1. Target Specific and induce signal transduction: cytokines binds to specific receptor on the cell membrane of target cell which triggers signal transduction pathway that ultimately alter gene expression in target cell. 2. High affinity: The affinity between cytokines ad their receptor is very high. Because of high affinity, cytokines can mediate biological effects at picomolar concentration. Microbiology| Cytokines 3. Action: a particular cytokine possess one of the following action: Autocrine action: the cytokine may binds with the membrane receptor of same cell that secrete it. Paracrine action: the cytokine may bind to the receptor on a target cell in close proximity to producer cell. Endocrine action: cytokine may binds to the target cell in distant part of the body. Microbiology| Cytokines Microbiology| Cytokines Biological functions of cytokines : Stimulate development of cellular and humeral immune response. Induction of inflammatory response. Regulation of hematopoiesis. Control of cellular proliferation and differentiation. Healing of wounds. Microbiology| Cytokines Cytokines family : Hematopoietin family. Chemokines family. Interferon family. Tumor necrosis factor (TNF) family. Colony stimulating factor (CSF) family. Microbiology| Cytokines Hematopoietin Family Cytokines : Members of the hematopoietin cytokine family are small, soluble cytokines that communicate between and among cells of the immune system. Microbiology| Cytokines Their cellular origins and target cells are as diverse as their ultimate functions, which range from: Signaling the onset of T- and B-cell proliferation. Signaling the onset of B-cell differentiation to plasma cells and antibody secretion. Signaling the differentiation of a T helper cell along one particular differentiation pathway versus another. Initiating the differentiation of particular leukocyte lineages (e.g., granulocyte monocytecolony stimulating factor GM-CSF, granulocyte - colony stimulating factor G-CSF). Microbiology| Cytokines Chemokines : Chemokines are a structurally related family of small cytokines that bind to cell-surface receptors and induce the movement of leukocytes up a concentration toward the chemokine source. This soluble factor-directed cell movement is known as chemotaxis, and molecules that can elicit such movement are referred to as chemoattractants. Microbiology| Cytokines Interferons : Interferon family represents a widely expressed group of cytokines. It includes three main classes, designated as type I IFNs, type II IFN and type III IFNs. The two main type I IFNs includes IFN-α (further classified into 13 different subtypes such as IFN-α1, -α2, -α4, -α5, -α6, -α7, -α8, -α10, -α13, -α14, -α16, -α17 and -α21), and IFN-β. Microbiology| Cytokines The term interferon derives from the ability of these cytokines to interfere with viral replication. Type I IFNs present a potent antiviral effect by inhibiting viral replication, increasing the lysis potential of natural killer (NK) cells and the expression of MHC class I molecules on virus-infected cells, and stimulating the development of Th1 cells. Microbiology| Cytokines During an infectious process, this type of interferon becomes abundant and is easily detectable in the blood. On the other hand, type II IFN has only one representative, IFN-γ. This cytokine plays a major role is macrophage activation both in innate and adaptive immune responses. Type III IFNs, also denoted IL-28/29, present similar biological effects to type I IFN, playing an important role in host defense against viral infections Microbiology| Cytokines Interleukins : Interleukins (ILs) are a group of secreted proteins with diverse structures and functions. These proteins bind to receptors and are involved in the communication between leukocytes. They are intimately related with activation and suppression of the immune system and cell division. The interleukins are synthesized mostly by helper CD4+ T lymphocytes, monocytes, macrophages and endothelial cells. Interleukins are named as IL plus a number. Microbiology| Cytokines Tumor necrosis factor (TNF) family : There are two members of the TNF family: TNF-α and TNF-β TNF-α (frequently referred to simply as TNF) is a proinflammatory cytokine, produced primarily by activated macrophages, but also by other cell types including lymphocytes, in response to infection, or inflammation. TNF-β is produced by activated lymphocytes and can deliver a variety of signals. On binding to neutrophils, endothelial cells lead to increased expression of MHC and of adhesion molecules. Microbiology| Cytokines Note: Fas ligand (FasL),which is member of this family induces apoptosis on binding to its receptor.