Immune Cytokines

Cytokines are small proteins that regulate and mediate immunity, inflammation, and hematopoiesis. They are secreted de novo in response to immune stimuli, and usually act briefly, locally, at very low concentrations (the exception being endocrine action at distant cells). Cytokines bind to specific membrane receptors, which then signal the cell via second messengers, often tyrosine kinases, to alter cellular activity (gene expression).

 Complement Receptors  Fc receptors  Immunoglobulins  Interferons  Scavenger Receptors  Toll-like Receptors  Cell Adhesion Molecules  Cell signaling  Receptor Tyrosine Kinases (RTKs)  Receptor Signal Transduction  Second Messengers

Cytokine
Producer cell/tissue
Target cell
Functions

Granulocyte/Monocyte Colony Stimulating Factor (CSF)

endothelium, macrophages

growth and differentiation of neutrophils
growth and differentiation of monocytes and dendritic cells
thymic epithelial cells (TEC), PMN, chondrocytes, glomerular mesangial cells, Ishikawa cells lymphohematopoietic growth and differentiation of monocytes, enhances expression of differentiation- antigens and stimulates chemotactic, phagocytic, and cytotoxic activities of monocytes

Interleukins

IL-1a IL-1b
costimulation
maturation and proliferation
activation
various
inflammation, acute phase response, fever
IL-2

hematopoietin

cell growth, proliferation, activation,

synthesis of antibodies

IL-3

(multi-CSF) hematopoietin

growth and differentiation
growth, and histamine release
IL-4

hematopoietin

proliferation and differentiation IgG1 and IgE synthesis
MHC Class II
proliferation
IL-5
proliferation and differentiation IgA synthesis
IL-6
pro-inflammatory
IL-6 receptor has two subunits - an alpha subunit that produces ligand specificity, and a p130 receptor subunit. Signals through JAK kinases and activation of Ras-mediated signaling
differentiation into plasma cells → secretion of antibodies
costimulator of T cells
differentiation
various
acute phase response

neurons, osteoblasts

neuronal differentiation, bone loss
IL-7
differentiation into progenitor B and T cells
IL-8
macrophages endothelial cells
chemotaxis
IL-10
inhibition of macrophage function, cytokine production
activation
IL-12
differentiation into CTL (with IL-2)
activation

Interferons  Interferons

IFN-a
various
viral replication MHC I expression
IFN-b
fibroblasts
various
viral replication MHC I expression
IFN-g
various
viral replication
MHC expression
Ig class switch to IgG2a
proliferation
pathogen elimination

Macrophage Inflammatory Proteins

MIP-1a
chemotaxis
MIP-1b
chemotaxis

Transforming Growth Factor

TGF-b
chemotaxis
activated macrophages
IL-1 synthesis
IgA synthesis
various
proliferation

Tumor Necrosis Factor

TNF-a
CAM and cytokine expression
cell death
TNF-b
lymphotoxin-α (LT)
phagocytosis, with no production; activation effector cells to infection sites, leukocyte adhesion to endothelial cells, peripheral lymphoid organogenesis, stimulation of B cells

cell death through inhibition of tumor angiogenesis

 Cell Adhesion Molecules  Cell signaling  Complement Receptors  Fc receptors  Immune Cytokines  Immunoglobulins  Receptor Tyrosine Kinases (RTKs)  Receptor Signal Transduction  Second Messengers  Scavenger Receptors  Toll-like Receptors

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. . . since 10/06/06