As cytokines (including cytokines , by ancient Greek κύτος kytos , vessel cavity 'and κίνησις kinesis , movement') are proteins referred to, which the growth and differentiation of cells regulate. They are a group of peptides that primarily initiate or regulate the proliferation and differentiation of target cells. Some cytokines are accordingly called growth factors , others play an important role in immunological reactions and inflammatory processes and can then be called mediators . There are essentially five main groups of cytokines: interferons , interleukins , colony-stimulating factors , tumor necrosis factors and chemokines .
In cell biology, the importance of cytokines is constantly increasing. Several cytokines are already commercially produced as recombinant proteins .
Interferons are cytokines that tell cells to make proteins that make them more resistant to viral infections. There are various interferons (IFN-ɑ, IFN-β and IFN-γ ) that are formed by leukocytes (especially monocytes and macrophages ) and fibroblasts and have an immune- stimulating , especially antiviral and antitumor effect. Interferons are also used as medicinal substances , especially for the treatment of multiple sclerosis or the chronic liver inflammation caused by viruses . The PEGylated interferon is mainly used here. This ensures a delayed and therefore longer-term release of the active ingredient. Side effects are possible here as pronounced flu-like symptoms , among other things .
Interleukins are cytokines that enable the immune defense cells (leukocytes) to communicate with one another in order to combat pathogens or tumor cells in a coordinated manner. Furthermore, certain interleukins such as IL-1β and IL-6, together with the tumor necrosis factor α, direct inflammatory reactions and systemic effects. These include B. the triggering of fever and generalized increases in blood flow and permeability, so that these cytokines can lead to circulatory failure in the event of sepsis . The blood really sinks into the peripheral tissue.
Colony Stimulating Factors (CSF)
Colony-stimulating factors are growth factors for red and white blood cells (→ hematopoietic growth factors ). This includes erythropoietin , which is produced by the kidney and stimulates the formation of red blood cells , but is also used as a medicinal substance for this purpose. An example of growth factors for white blood cells is G-CSF (Granulocyte Colony Stimulating Factor). There are therapeutic uses for renal insufficiency , bone marrow damage after chemotherapy, or myelodysplastic syndrome (MDS).
Tumor Necrosis Factors (TNF)
Tumor necrosis factors are mainly secreted by macrophages and can lead to the classic inflammatory symptoms of heat, swelling, reddening and pain.
Chemoattractors or chemical attractants cause cells with suitable receptors to migrate to the source of the chemokines ( chemotaxis : orientation movement of the immune cells triggered by chemical stimuli ).
The receptors for cytokines can be divided into seven groups:
Hematopoietin family of receptors, receptors for IL-2, IL-3, IL-4, IL-5, IL-7, IL-9, IL-11, IL-12, IL-13, IL-15
erythropoietin (EPO), Thrombopoietin (TPO), anti-leukemia factor (LIF), G-CSF, GM-CSF
- Interferon receptor family, receptors for IFNa / b, IFNg, IL-10
- TNF -receptor family ( death receptors ), receptors for TNFα, TNFβ, FasL, CD27, CD30, CD40 (trimeric receptors)
Immunoglobulin (Ig) superfamily receptors,
receptors for IL-1a, IL-1b (but also BCR, TCR, MHC, etc.)
Tyrosine kinase receptors,
receptors for M-CSF, SCF
- Ras / Raf pathway
- Jak / STAT pathway
- Serine / threonine kinase receptors, receptors for TGFβ and the like a.
- Chemokine receptors (7TMHR)
The cytokine storm is an overreaction of the immune system . In the process, large amounts of inflammatory messenger substances are released.
- "Cytokines and Cells Online Pathfinder Encyclopaedia" (English)
- Molecular mechanisms of cytokine-controlled inflammatory processes: signal transduction and pathophysiol. Consequences / SFB 542 ( Memento from September 21, 2011 in the Internet Archive )