Cytokines

Cytokines, small proteins (about 5-20 kDa), are very important in human health and disease, specifically in host responses to infection, immune responses, inflammation, trauma, sepsis, cancer, and reproduction. Similar to hormones, cytokines are important in cell signaling: released by certain types of cells, they affect the behavior of other cells and sometimes the releasing cell itself. Different from hormones, cytokines circulate in much higher concentrations and are produced by various types of cells, such as immune cells like macrophages, B lymphocytes, T lymphocytes and mast cells, endothelial cells, fibroblasts, and stromal cells. More than one type of cells may produce the same cytokine. Cytokines act through receptors to modulate the balance between humoral and cell-based immune responses. Cytokines regulate the maturation, growth, and responsiveness of particular cell populations. Some cytokines enhance or inhibit the action of other cytokines in complex ways.

Cytokines can be classed as the following based on their presumed functions, cell of secretion, or target of action:

Interleukins – produced mainly by T-helper cells.
Chemokines – mediating chemoattraction (chemotaxis) between cells.
Lymphokines – produced by lymphocytes.
Monokines – produced primarily by monocytes and macrophages.
Interferons – involved in antiviral responses.
Colony stimulating factors – supporting the growth of cells in semisolid media.

Interleukins:

Type I (grouped by receptor subunit):

γ-chain subfamily:
IL2 / IL15
IL4 / IL13
IL7
IL9
IL21

β-chain subfamily:
IL3
IL5
GM-CSF

IL6 like/gp130 subfamily:
IL6
IL11
IL27
IL30
IL31
+non IL OSM
LIF
CNTF
CTF1

IL-12/IL12RB1 subfamily:
IL12
IL23
IL27
IL35

Others:
IL14
IL16
IL32
IL34

Type II:

IL 10 subfamily:
IL10 / IL22
IL19
IL20
IL24
IL26
Interferon type III (IL28 / IFNL2+3 and IL29 / IFNL1)

Interferon I subfamily:
IFNA1
IFNA2
IFNA4
IFNA5
IFNA6
IFNA7
IFNA8
IFNA10
IFNA13
IFNA14
IFNA16
IFNA17
IFNA21
IFNB1
IFNK
IFNW1

Interferon II subfamily:
IFNG

Ig superfamily:

IL1A / IL1F1
IL1B / IL1F2
1Ra / IL1F3
IL1F5
IL1F6
IL1F7
IL1F8
IL1F9
IL1F10
IL-33 / IL1F11
IL-18 / IL1G

IL 17 family:

IL17/IL25 (IL17A)

Chemokines:

CCL subfamily:
CCL1
CCL2 / MCP-1
CCL3 / MIP-1α
CCL4 / MIP-1β
CCL5 / RANTES
CCL6
CCL7
CCL8
CCL9
CCL11
CCL12
CCL13
CCL14
CCL15
CCL16
CCL17
CCL18 / PARC / DC-CK1 / AMAC-1 / MIP-4
CCL19
CCL20
CCL21
CCL22
CCL23
CCL24
CCL25
CCL26
CCL27
CCL28

CXCL subfamily:
CXCL1/KC
CXCL2
CXCL3
CXCL4
CXCL5
CXCL6
CXCL7
CXCL8 / IL8
CXCL9
CXCL10
CXCL11
CXCL12
CXCL13
CXCL14
CXCL15
CXCL16
CXCL17

CX3CL subfamily:
CX3CL1

XCL subfamily:
XCL1
XCL2

TNF:

TNFA
Lymphotoxin
TNFB/LTA
TNFC/LTB
TNFSF4
TNFSF5/CD40LG
TNFSF6
TNFSF7
TNFSF8
TNFSF9
TNFSF10
TNFSF11
TNFSF13B
EDA

Monokines:

Interleukin 1 (IL1-alpha and IL1-beta)
TNF-alpha
TNF-beta / LTA
CSF1
GM-CSF
G-CSF

Lymphokines:

Th1 subfamily:
IFNG
TNFB

Th2 subfamily:
IL4
IL5
IL6
IL10
IL13

Others:

KITLG
Colony-stimulating factors: CSF1/M-CSF, CSF2/GM-CSF, and CSF3/G-CSF
SPP1

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