. What is cytokine ?
cytokine is a small molecule protein with extensive biological activity synthesized and secreted by immune cells (such as monocytes, macrophages , T cells, B cells , NK cells, etc.) and certain non-immune cells (endothelial cells, epidermal cells, fibroblasts, etc.). It has various functions such as regulating innate and adaptive immunity, hematopoietic immunity, hematopoietic immunity, cell growth, , APSC pluripotent cells, and repair of damaged tissues.
2. Common characteristics of cytokines
Cytokines are mostly glycoprotein , with a molecular weight of generally 10-25KDa, and some 8-10kDa. Most cytokines exist in monomer form, a few cytokines play biological roles in dimers, trimers or tetramer form, such as IL-5, IL-12, M-CSF, TGF-β, etc. as dimers, TNF-α, LT-α as trimers, and IL-16 in tetramer form binds to the corresponding receptor.
(I) Production and secretion characteristics: acts on nearby cells or other components through paracrine or autocrine forms, and plays a brief role in local and at high concentrations. The systemic effect is triggered by endocrine action on distant target organs.
(Bi) High efficiency: After cytokines bind to receptors on the cell surface, they pass through receptor-mediated signals to perform regulatory and effector functions efficiently. Generally, the pmol/L (10-12mol/L) level has obvious biological effects.
(III) Plevovoraciality: The same cytokine has different categories of functions.
(IV) Overlapability: multiple cytokine members show the same activity.
(V) Synergy: different cytokines work together.
(VI) Antagonism: different cytokines have opposite effects on the same target.
3. Classification of cytokines
(I) Interleukin (IL): It was named in 1979, including lymphocyte , monocyte and other non-monocyte-generated cytokines play an important role in cell-interaction, immunomodulation, hematopoiesis and inflammation.
(Bi) Colony stimulation factor (CSF) : According to its stimulation of hematopoietic stem cells or hematopoietic progenitor cells at different differentiation stages, they form different cell colonies in semi-solid culture medium, namely granulocyte colony stimulation factor (G-CSF), macrophage colony stimulation factor (M-CSF), granulocyte-macrophage colony stimulation factor (GM-CSF), multiple colony stimulation factor (IL-3), stem cell factor (SCF), erythropoietin (EPO), thrombocytopenin (TPO), etc.
(III) Interferon (IFN): was initially named Interferon because it was discovered that virus-infected cells could produce one substance that could interfere with the infection and replication of another virus. According to the source and structure, interferons are divided into IFN-α, IFN-β, IFN-γ and IFN-λ, which are mainly produced by leukocytes , fibroblasts and activated T cells, respectively.
(IV) Tumor necrosis factor (TNF): was originally found to cause necrosis of tumor tissues and was named. According to its source and structure, it is divided into three categories: TNF-α, TNF-β (LT-α) and LT-β. TNF-α is produced by monocytes/macrophages. LT-α is also known as lymphotoxin, which is produced by activated T cells. LT-β is a membranous lymphotoxin.
(V) Convert growth factor (TGF-β): is produced by a variety of cells. There are more than 20 members of this family, such as TGF-β1, TGF-β2 and bone-forming protein (BMP).
(VI) Chemokine family: includes four subfamilies, ① C-X-C subfamily or α subfamily, mainly chemotaxis neutrophils, and the main members are IL-8, melanoma growth active factor (GRO), platelet basic protein (PBP), etc.; ② C-C subfamily or β subfamily, mainly chemotaxis monocytes.③C subfamily, only one member Fractalkine; ④XC subfamily, two members of lymphocyte chemokines (LTN) and SCM-1β are found.
(VII) Other cytokines: epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), hepatocyte growth factor (HGF), insulin-like growth factor (IGF-1) and IGF-II, vascular endothelial cell growth factor (VEGF), etc.
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Article source: Biology Teaching
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