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Cytokines Dr.Ghada Boghdadi. Objectives: List the surface and secreted molecules involved in immune interactions. Explain the effects of each cytokine. Identify the function of cytokines and interleukins in cell-mediated immunity.
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Cytokines Dr.Ghada Boghdadi
Objectives: • List the surface and secreted molecules involved in immune interactions. • Explain the effects of each cytokine. • Identify the function of cytokines and interleukins in cell-mediated immunity. • Discuss the role of interferons in the prevention of infections. Anantha Narayanan Ch 15
Cytokines: • Low MW non-antibody proteins • act as mediators between cells • Secreted by a variety of cells • Important role in the induction • and regulation of immune responses • Stimulus is required for production • High affinity binding to specific receptors • Induce gene activation
A cytokine can be pleiotropic (different effect on different cells)
Monokines, cytokines produced by mononuclear phagocytic cells • Lymphokines, cytokines produced by activated lymphocytes, especially Th cells • Interleukins, cytokines that act as mediators between leukocytes • Categories: • TNF family • Chemokine family • Interferon family • Hematopoietin family • ILs • TGFs
Functions: Regulate hematopoiesis Innate immune responses Inflammation Specific immune responses
Mediators of natural immunity: • TNF, IL1, IL10, IL12, type I IFN, IFN-γ • B. Mediators of adaptive immunity: • IL2, IL4, IL5, TGB-β • C. Stimulators of hematopoesis: • M-CSF, GM-CSF
http://www.microvet.arizona.edu/courses/MIC419/Tutorials/cytokines.htmlhttp://www.microvet.arizona.edu/courses/MIC419/Tutorials/cytokines.html
Cytokine antagonists- two mechanisms Inhibitor binds to receptor and blocks it (e.g., IL-1Ra) Soluble receptors bind to cytokines so they can’t bind to membrane-bound receptors (soluble IL-2 receptor among many others; released in chronic T-cell activation)
Interferons Type I: IFN-α, IFN- Type II:IFN- They are antiviral and possess antioncogenic properties. Macrophages and natural killer cell activation. Enhancement of MHC classes I and II, and thus presentation of foreign (microbial) peptides to T cells.
Intracellular virus, bacteria No IL-4 APC Th Th1 IL-12 IFN-α NK IFN-
When a tissue cell is infected by a virus, it releases interferon. Interferon will diffuse to the surrounding cells. When it binds to receptors on the surface of those adjacent cells, they begin the production of a protein that prevents the synthesis of viral proteins. This prevents the spread of the virus throughout the body.