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→Bacterial toxic shock
|interleukins || IL || IL-1, IL-2
|interleukins || IL || IL-1, IL-2
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|interferons || IFN || IFN-alpha
|interferons || IFN || IFN-γ
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|tumour necrosis factors || TNF || TNF-alpha
|tumour necrosis factors || TNF || TNF-α
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|growth factors || GF || NGF, EGF
|growth factors || GF || NGF, EGF
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|chemokines || - || RANTES, MCP-1
|chemokines || - || RANTES, MCP-1
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|}
==Functions of cytokines==
==Functions of cytokines==
'''Mediating and regulating innate immunity''': bacterial and viral products, such as LPS, stimulate macrophages and natural killer cells to secrete cytokines that primarily act on endothelial cells and leukocytes. They stimulate the early stages of the inflammatory reaction to microbes.
'''Mediating and regulating innate immunity''': bacterial and viral products, such as LPS, stimulate macrophages and natural killer cells to secrete cytokines that primarily act on endothelial cells and leukocytes. They stimulate the early stages of the inflammatory reaction to microbes.
Cytokines primarily produced by '''macrophages''':
Cytokines primarily produced by '''macrophages''':
*GM-CSF (granulocyte macrophage colony stimulating factor)- stimulates growth and differentiation of granulocytes, macrophages, [[Neutrophils|neutrophils]] and eosinophils
*GM-CSF (granulocyte macrophage colony stimulating factor)- stimulates growth and differentiation of granulocytes, macrophages, [[Neutrophils|neutrophils]] and eosinophils
*IL-1 - stimulates TH<sub>2</sub> cells and acute phase response
*IL-1 - stimulates T<sub>H</sub>2 cells and acute phase response
*IL-6 - stimulates growth and differentiation of B and T cells and acute phase response
*IL-6 - stimulates growth and differentiation of B and T cells and acute phase response
*IL-12 - stimulates TH<sub>1</sub> cells
*IL-12 - stimulates T<sub>H</sub>1 cells
*IL-18 - stimulates IFN-gamma production by T cells and NK cells, favours Th1 response
*IL-18 - stimulates IFN-gamma production by T cells and NK cells, favours Th1 response
*TNF-α - stimulates local inflammation and endothelial activation
*TNF-α - stimulates local inflammation and endothelial activation
Cytokines primarily produced by '''TH<sub>1</sub> cells''':
Cytokines primarily produced by '''T<sub>H</sub>1 cells''':
*IL-2 - stimulates proliferation and differentiation of T cells, activates NK cells and macrophages
*IL-2 - stimulates proliferation and differentiation of T cells, activates NK cells and macrophages
*IFN-γ - activates macrophages, increases expression of MHC I and II molecules, increases antigen presentation
*IFN-γ - activates macrophages, increases expression of MHC I and II molecules, increases antigen presentation
*TNF-β - stimlulates killing mechanisms in T and B cells and endothelial activation
*TNF-β - stimlulates killing mechanisms in T and B cells and endothelial activation
Cytokines primarily produced by '''TH<sub>2</sub> cells''':
Cytokines primarily produced by '''T<sub>H</sub>2 cells''':
*IL-4 - activates B cells and [[IgE]] switch, supresses Th1 cells
*IL-4 - activates B cells and [[IgE]] switch, supresses T<sub>H</sub>1 cells
*IL-5 - stimulates eosinophil growth and differentiation
*IL-5 - stimulates eosinophil growth and differentiation
*IL-10 - suppresses macrophage functions
*IL-10 - suppresses macrophage functions
Although [[Neutrophils|neutrophils]] produce a lower amount of cytokines per cell than other immune cell types, they are often the first and most common cell type present at sites of infection. This makes them a physiologically important source of cytokines, such as IL-12.
Although [[Neutrophils|neutrophils]] produce a lower amount of cytokines per cell than other immune cell types, they are often the first and most common cell type present at sites of infection. This makes them a physiologically important source of cytokines, such as IL-12. [[Eosinophils|Eosinophils]] and [[Mast Cells|Mast cells]] also produce a number of cytokines that are important in the immunology of [[Immunity to Parasites|parasites]] and the pathology of allergic reactions.
==Chemokines==
==Chemokines==
*Lymphoid trafficking
*Lymphoid trafficking
*Wound healing
*Wound healing
*TH<sub>1</sub>/TH<sub>2</sub> development
*T<sub>H</sub>1/T<sub>H</sub>2/T<sub>H</sub>17 development
*Angiogenesis/angiostasis
*Angiogenesis/angiostasis
*Lymphoid organ development
*Lymphoid organ development
*''S. aureus''- produces enterotoxins and toxic-shock syndrome toxin
*''S. aureus''- produces enterotoxins and toxic-shock syndrome toxin
*''M. arthritidis''
*''M. arthritidis''
The large number of T cells activated by such toxins (between 5-25% of all T cells, compared to less than 0.01% activated towards conventional antigens) means an excessive amount of cytokines produced, such as IL-1 and TNF. These elevated amounts cause the same systemic reactions as seen in bacterial septic shock.
*''S. pyogenes''
The large number of T cells activated by such toxins (between 5-25% of all T cells, compared to less than 0.01% activated towards conventional antigens) means an excessive amount of cytokines produced, such as IL-1 and TNF. These elevated amounts cause the same systemic reactions as seen in bacterial septic shock.
===Lymphoid and myeloid cancers===
===Lymphoid and myeloid cancers===
The excessive production of cytokines has been linked to some types of cancer, e.g. IL-6 has been shown to be secreted by myeloma cells, plasmacytoma cells and cervical and bladder cancer cells. IL-6 is known to act in an autocrine manner to stimulate cell proliferation.
The excessive production of cytokines has been linked to some types of cancer, e.g. IL-6 has been shown to be secreted by myeloma cells, plasmacytoma cells and cervical and bladder cancer cells. IL-6 is known to act in an autocrine manner to stimulate cell proliferation.