Cytokinis (CAT 1) PDF

Cytokines Prof. ASIT RANJAN GHOSH/ SBST https://www.youtube.com/watch?v=9wdZLvNKyQY What are cytokines? ⚫ “Cytokines” are soluble protein secreted by the cells of innate and adaptive immunity and therefore mediate many of the functions of these cells ⚫ Based on their cellular sour...

Cytokines Prof. ASIT RANJAN GHOSH/ SBST https://www.youtube.com/watch?v=9wdZLvNKyQY What are cytokines? ⚫ “Cytokines” are soluble protein secreted by the cells of innate and adaptive immunity and therefore mediate many of the functions of these cells ⚫ Based on their cellular sources monokines (mononuclear phagocyte) lymphokines (lymphocytes) interlukins (leukocytes) (IL-1, IL-2, etc.) ⚫ A subfamily of cytokines primarily functions in directing migration of cells, these are called “chemotactic cytokines” or “chemokines” What are cytokines? figure 12-01a INDUCTION ⚫ Cytokines are polypeptides produced by the cells of innate and adaptive immunity in response to microbes and other antigens as a result of cellular activation. PRODUCTION ⚫ Cytokines initiate their actions by binding to specific membrane receptors on target cells. ⚫The cellular responses to most cytokines consist of gene ACTIVATION activation, resulting in the expression of new functions and sometimes the proliferation of the target cells Cytokines ⚫ General Properties ⚫ Functional Categories of Cytokines ⚫ Cytokine Receptors ⚫ Biologic Actions Cytokines ⚫ General Properties ⚫ Functional Categories of Cytokines ⚫ Cytokine Receptors ⚫ Biologic Actions Phagocytes-identify, ingest, and destroy microbes ⚫Mononuclear phagocytes ⚫Neutrophils (polymorphonuclear leukocytes) Short-lived (6h); the most abundant population of circulating WBCs; mediate the earliest phase of inflammatory response As a result of cellular activation: Mononuclear phagocytes are the principal source of cytokines of innate immunity ⚫ Tumor necrosis factor (TNF) ⚫ IL-1 ⚫ IL-12 ⚫ Type I IFNs ⚫ IL-15 ⚫ IL-18 NK cells secret cytokine, mainly IFN-—to activate macrophage to destroy phagocytosed microbes. Cytokine actions may be local and systemic Autocrine act on cytokine-producing cell itself action 2-Juxtacrine action Paracrine action act on a nearby cell circulation Endocrine action act at a distance from the site of infection  [ one act on different cells ] The action of cytokines ◼pleiotropism [ different act independently on one cell ] ◼redundancy ◼synergy ◼antagonism SYNERGY : two act together on one cell ANTAGONISM : one acts and other block its action Cytokines ⚫ General Properties ⚫ Functional Categories of Cytokines ⚫ Cytokine Receptors ⚫ Biologic Actions Functional Categories of Cytokines ⚫ Mediators and regulators of innate immunity Tumor necrosis factor (TNF), IL-1, IL-6, IL-12, Type I IFNs, IL-15, IL-18,chemokines ⚫ Mediators and regulators of adptive immunity IL-2, IL-4, IL-5, IFN-g, TGF-, LT(TNF- ), IL-13,etc ⚫ Stimulators of hematopoiesis granulocyte-CSF, G-CSF macrophage-CSF，M－CSF granulocyte-macrophage-CSF, GM-CSF) erythropoietin, EPO thrombopoietin, TPO stem cell factor, SCF Innate and adaptive Immunity Most cytokines act close to where they are produced ⚫ T lymphocytes often secret cytokines at the site of contact with antigen-presenting cells. Cytokines ⚫ General Properties ⚫ Functional Categories of Cytokines ⚫ Cytokine Receptors ⚫ Biologic Actions Cytokine Receptors ⚫ Type I cytokine receptors ⚫ Type II cytokine receptors ⚫ Ig superfamily ⚫ TNF receptors ⚫ Seven-transmembrane -helical receptors *Classification of cytokine receptors based on structural homologies among the extracellular cytokine-binding domain. Cytokine receptors and signaling Different cytokines binding to cytokine receptors activated distinct signal transduction pathways resulting in gene activation.  Cytokines typically activate second messenger systems, like JAK-STAT pathways, as illustrated on the left side of the diagram. Conversely, hormones typically activate different signaling pathways, like G protein-coupled receptors, seen at the top of the figure. https://en.wikipedia.org/wiki/Cytokine# Cytokines ⚫ General Properties ⚫ Functional Categories of Cytokines ⚫ Cytokine Receptors ⚫ Biologic Actions Biologic Actions ⚫ Cytokines That Mediate and Regulate Innate Immunity ⚫ Cytokines That Mediate and Regulate Adaptive Immunity ⚫ Cytokines That Stimulate Hematopoiesis Pluripotent stem cells HSC In summary What are cytokines? Cytokines that mediate innate immunity Cytokines that mediate adaptive immunity Cytokines That Stimulate Hematopoiesis