Cytokines: what are they, what types are there and what are their functions?
These types of proteins play an important role in the immune system of the human body.
You have probably heard of cytokines.. But what exactly are they? What are they for? Who makes them? What is their biological purpose?
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.
What are cytokines?
The 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 to do.depending on what our organism needs.
In this article we will talk about cytokines and their biochemistry, their properties, to whom they send messages, what their functions may be in the organism 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 proteins, of low molecular weight, act through complex interactions between different types of cells..
These proteins are part of the immune system and their function is as follows: imagine a small molecule, which is produced by a cell that receives a stimulus.
This molecule This molecule travels to its receptor (which is located in another cell) to give a signal or message. (these receptors are found in the membranes of cells). This second cell will give a response, and from there an intracellular signal transduction cascade is initiated. This cascade will trigger a specific biological response.
Characteristics of cytokines
Cytokines are very different and complex molecules, although they share a number of characteristics that we will detail below. which are detailed below.
Being part of the immune system, they are produced mainly by macrophages, which are essential molecules in the innate immune system.. Recall that the innate immune system is the one that involves cells recognizing pathogens in a generic way and attacking them.
If we talk about the specific immune system, the helper T cells are the ones in charge of producing cytokines. The specific immune system is one that, as its name suggests, has specificity; that is, the cells attack pathogens in a generic form and attack them.i.e. the cells specifically attack specific pathogen receptors.
Cytokine production is relatively short (transient) and is dependent on the duration of the stimulus (i.e. the pathogen in the case of macrophages and T cells).
Other characteristics are the following:
- They possess pleiotropy; that is, they trigger multiple effects after acting on different cells.
- They are redundant, i.e. different cytokines can produce the same effect.
- They can be synergistic, i.e. they have a potentiating effect on each other.
- They can be antagonistic, i.e. they can block each other.
- Cytokines have different affinity to their specific receptor.
There are several classifications of cytokines, as these are very complex moleculeswith different origins and different functions. Here we show you different classifications:
According to cytokine interactions 2.
Basically, the interactions are between lymphoid cells (immune system cells), inflammatory cells, and hematopoietic cells (blood cells). (blood cells).
But these interactions can be of different types, and depending on these types, we obtain a classification of cytokines:
1. 1. Autocrine cytokines.
These are cytokines that act on the same cell that produces them..
1. 2. Paracrine cytokines
Cytokines that act in the region adjacent to the site of secretion.
1. 3. Endocrine cytokines
Cytokines that act in regions distant from where they are secreted.. These cytokines travel through the Blood and their function is to act on the different tissues.
2. According to the functions of cytokines
Cytokines, being such diverse and complex molecules, can perform a wide variety of functions. Here we will classify them into the most essential ones:
2. 1. Pro-inflammatory function.
They are proinflammatory cytokines; they act in the innate immune responseinflammation or inflammation.
2. 2. Developmental, cell maturation, and/or cytotoxicity function.
They act at different times of the cell cycle to shape cell development, maturation and/or death.
2. 3. Producing functions of different immunoglobulins
These are the proteins that protect us from infections.
2. 4. Hematopoietic functions
They are those cytokines involved in the development and maturation of the blood cells (red blood cells (red blood cells, white blood cells and platelets essentially).
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. It is these receptors that will determine the response that will be triggered by the effector cell. This variety of receptors is grouped into the five so-called cytokine receptor families.
1. Immunoglobulin superfamily
These are the receptors for the well-known antibodies, which are the essential molecules created by the body to essential molecules that the body creates to attack pathogens in a specific way..
2. Class I family of cytokine receptors
This family of receptors constitutes the receptors for hematopoietins, i.e. blood cells.
3. Class II family of cytokine receptors
This family of receptors constitutes the interferon receptors. Recall that interferons are proteins manufactured by the body in response to pathogens (viruses, bacteria, parasites...).
4. Family of TNF (tumor necrosis factor) receptors
These are molecules that mediate the processes of inflammation and cell death.
5. Family of chemokine receptors
The latter group of cytokine receptors are particularly peculiar: they are so called because they are able to attract and direct other cells of the immune system to repair tissues. they are able to attract and direct other cells of the immune system to repair tissues..
Of all these "superfamilies" mentioned above, there are several subgroups of each. That is, for example, there are many TNF receptors that are named TNF-ɑ and TNF-ᵦ, various types of class I family receptors, class II family receptors, etc.
Each superfamily, as we have already seen, is involved in specific molecular mechanisms.
The best known cytokines
Of all the cytokines that can be produced by the organism, interleukins (IL) are among the most important cytokines.. This type of cytokine is mainly produced by lymphocytes and macrophages, but can also be produced by endothelial cells, adipose cells, endothelial cells, muscle cells, etc.
Its fundamental action consists of regulating inflammation through various mechanisms.. They are generally classified as proinflammatory 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 organism is a complex system where many needs are orchestrated and measured by cytokines so that the body can function properly through a stimulus-response mechanism.
- Feduchi Canosa, Elena (2014). Bioquímica. Conceptos esenciales. Editorial Médica Panamericana S.A.; second edition.
- Nelson, David L, Cox, MICHAEL M. (authors), Cuchillo Foix, Claudi M. (Translator). (2018). Principles of biochemistry. Lehninger Publishing House; seventh edition.
- Tortora, Gerard J., Derrickson, Bryan (2018). Principles of Anatomy and Physiology. Editorial Médica Panamericana S.A.; fortnightly edition.
(Updated at Mar 28 / 2023)