Cytokines: What They Are, What Types There Are And What Functions They Have
You’ve probably heard of cytokines But what exactly are they? What are they for? Who manufactures them? What biological meaning do they have?
We could say that basically cytokines are like our body’s messengers, which serve to transmit messages between our cells when they need to perform a specific function.
Cytokines (also called cytokines) are proteins that cells generate and act by sending signals between different types of cells depending on what our body needs.
In this article we will talk about cytokines and their biochemistry, their properties, who they send messages to, what their functions may be in the body and finally what types exist.
What are they for?
As we have already mentioned, cytokines are proteins that cells make when they want to communicate with each other. These low molecular weight proteins act through complex interactions between different types of cells
These proteins are part of the immune system and their operation is as follows: imagine a small molecule, which is produced by a cell that receives a stimulus.
This molecule travels to its receptor (located in another cell) to give a signal or message (these receptors are found in cell membranes). This second cell will give a response, and from there an intracellular signal transduction cascade begins. This cascade will trigger a specific biological response.
Cytokines They are very different molecules and very complex, although they share a series of characteristics which we will see detailed below.
Being part of the immune system, They are produced mainly by macrophages, which are essential molecules in the innate immune system Let us remember that the innate immune system is the one that implies that cells recognize pathogens in a generic way and attack them.
If we talk about the specific immune system, T helper cells are responsible for producing cytokines. The specific immune system is one that, as its name indicates, has specificity ; That is, the cells specifically attack specific pathogen receptors.
Cytokine production is relatively brief (transient) and is dependent on the duration of the stimulus (that is, the pathogen in the case of macrophages and T cells).
Other features are the following:
Classifications
There are several classifications of cytokines, since these are very complex molecules, with different origins and different functions. Here we show you different classifications:
1. According to cytokine interactions
Basically, the interactions occur between lymphoid cells (immune system cells), inflammatory cells, and hematopoietic cells (blood cells).
But these interactions can be of different types, and based on these types, we obtain a classification of cytokines:
1. 1. Autocrine cytokines
They are those cytokines that they act on the same cell that produces them
1. 2. Paracrine cytokines
They are those cytokines that act in the region adjacent to the site of secretion.
1. 3. Endocrine cytokines
They are those cytokines that act in regions distant from where they have been secreted These cytokines travel through the blood and their function is to act on different tissues.
Cytokines, being such diverse and complex molecules, They can perform very wide variety of functions Here we will classify them into the most essential:
2. 1. Pro-inflammatory function
They are proinflammatory cytokines; act on the innate immune response nonspecific or inflammation.
They act at different moments of the cell cycle to model the development, maturation and/or death of cells.
2. 3. Producing functions of different immunoglobulins
They are the proteins that protect us from infections.
2. 4. Hematopoietic functions
Are those cytokines involved in the development and maturation of blood cells (red blood cells, white blood cells and platelets essentially).
Cytokine receptors
As we have already seen, cytokines must interact with a receptor on a cell to trigger a response.
There is a wide variety of cytokine receptors. These receptors are what will determine the response that the effector cell will trigger. This variety of receivers It is grouped into the five so-called cytokine receptor families
1. Immunoglobulin superfamily
They are the receptors of the well-known antibodies, which are the essential molecules created by the body to specifically attack pathogens
2. Class I family of cytokine receptors
This family of receptors constitutes the hematopoietin receptors, that is, blood cell receptors.
3. Class II family of cytokine receptors
This family of receptors constitutes interferon receptors Let us remember that interferons are proteins that the body produces in response to pathogens (viruses, bacteria, parasites…).
4. TNF (tumor necrosis factor) receptor family
They are the molecules that mediate the processes of inflammation and cell death.
This last group of cytokine receptors are especially peculiar: they are so called because They are able to attract and direct other cells of the immune system to repair tissues
Subgroups
Of all these “superfamilies” mentioned, there are various subgroups of each one. That is, for example, there are many TNF receptors named TNF-ɑ and TNF-ᵦ, several types of receptors from the class I, class II family, etc.
Each superfamily, as we have already seen, is involved in specific molecular mechanisms.
The best known cytokines
Of all the cytokines that the body can produce, interleukins (IL) are one of the most important cytokines These types of cytokines are mainly produced by lymphocytes and macrophages, but they can also be produced by endothelial cells, adipose cells, endothelial cells, muscle cells, etc.
Its fundamental action consists of regulating inflammation through various mechanisms In general they are classified as pro-inflammatory and anti-inflammatory.
The other cytokines, also essential for the inflammatory response, are Tumor Necrosis Factor Alpha (TNF-α) and interferons. All of them proinflammatory proteins
As you can see, the body is a complex system where many needs are orchestrated and measured by cytokines so that the body can function correctly through a stimulus-response mechanism.
