Our body's secret messengers: Let's learn about cytokines in a simple way!

Have you ever thought that when our bodies get sick or injured, a huge battle takes place inside to heal? We have our own very skilled army to fight off enemies like viruses and bacteria that come from outside our bodies. We call this the immune system. So there has to be someone to command this army, to exchange messages, and to send them exactly where the enemies are. Those secret messengers are the cytokines we are talking about today.

What exactly are cytokines?

Simply put, cytokines are small proteins that send messages between cells in our immune system. It's like a 'WhatsApp group' inside our bodies. When a threat like an infection or an injury comes to the body, immune cells release these messages called cytokines. These messages tell other immune cells, "There's a problem here, come quickly!", "This is the type of enemy we need to fight," and "Make more soldiers."

Imagine a virus entering your body. At that time, some cells send out these cytokine messages, telling other cells to get ready to fight the virus. This means that without these little messengers, our immune system wouldn't be able to function properly. These cytokines help keep our immune system healthy, even when there's no threat.

Are there main types of these cytokines?

Yes, just like there are different ranks in the army, there are different types of cytokines. Each type has a specific job. Let's look at some of the main types.

Additionally, some cytokines are named according to the type of cell that produces them:

• Lymphokines: Produced by a type of white blood cell called lymphocytes.
• Monokines: Produced by a type of white blood cell called monocytes.

The main function of cytokines: controlling inflammation

When most people hear the word 'inflammation', they think it's a bad thing, a sign of illness. But inflammation is actually an important sign that our immune system is fighting off enemies or repairing damaged tissue. Imagine if you cut your finger, it would be red, swollen, and a little hot, right? That's what inflammation is.

Cytokines mainly signal the following:

• Cell activation: Telling cells where to go and what to do. For example, directing immune cells to the site of an infection.
• Cell differentiation: An immature cell is told to "become a special type of white blood cell that can fight this disease."
• Cell proliferation: A signal to make more cells, or more cells. For example, this signal is given when more white blood cells are needed to fight a major infection.

Pro-inflammatory and anti-inflammatory cytokines

This is like the accelerator and brakes of a car. Both are essential for precisely controlling the response of our immune system.

• Pro-inflammatory cytokines: These are the accelerators . When a germ comes in, they cause inflammation and accelerate the immune response. These are the ones who give the signal to start the fight.
• Anti-inflammatory cytokines: These are the brakes . After defeating the enemy, they stop the further damage to our own healthy tissues by reducing inflammation and bringing everything back to normal.

How does this message exchange happen?

This is a very interesting process. Let's compare it to a key and a keyhole.

A cytokine is like a key . On the surface of the cell that needs to receive the message, there is a keyhole (receptor) that fits that key. When the cytokine (the key) goes and connects to the receptor (the keyhole) on that cell, that cell receives the message. Then that cell acts according to that message.

There are three ways to send these messages:

1. Autocrine signaling: A cell sends a message to itself.

2. Paracrine signaling: A cell sends messages to nearby cells.

3. Endocrine signaling: A cell sends messages through the blood to cells far away from it.

Which cells produce the most cytokines?

Cytokines are often produced by cells in our immune system. However, they are not the only cells. Other types of cells in our body can also produce them.

Immune cells

• Macrophages
• Dendritic cells
• Lymphocytes
• Monocytes
• Neutrophils
• Basophils
• Eosinophils
• Mast cells

Other cells

• Endothelial cells (cells lining the inside of blood vessels)
• Epithelial cells are the cells that cover the surface of our organs.
• Cells in connective tissue (Fibroblasts, Stromal cells)
• Cells surrounding nerves (Schwann cells)

What happens if cytokine balance is lost?

Although cytokines are essential for our health, like anything else, too much of them is not good. Sometimes, due to an infection or certain treatments, the immune system becomes overstimulated and starts producing excessive amounts of cytokines out of control.

We call this condition Cytokine Release Syndrome (CRS) or cytokine storm . It's like our own immune system goes berserk, attacking not only our enemies but also our own healthy cells. This can lead to excessive inflammation, tissue damage, and a variety of illnesses.

Diseases that can be caused by excess cytokines:

• Autoimmune diseases: In this, the immune system mistakenly attacks its own healthy cells.
• Metabolic disorders: Problems with the process of converting food into energy.
• Cancer.
• Sepsis: This is a very serious condition. Severe inflammation in the body causes reduced blood flow to major organs. This is a medical emergency and can be fatal if left untreated.

If you have any doubts about this condition, it is very important to see your doctor immediately for advice .

Cytokine panel test

Doctors can tell if your body has too many or too few cytokines. The blood test is called a cytokine panel . It measures the levels of cytokines in your blood that are involved in inflammation. Based on the results, your doctor can prescribe treatments to control inflammation if you have too many.