What Are Cytokines, Types, and Role in Inflammatory Immune Response?

Medically Reviewed By Angelica Balingit, MD
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Cytokines are proteins that mainly help immune system cells talk to each other. They play a role in managing immune system response, including against cancer and infection. They also have a role in signaling blood cells and inflammatory cells. There are many different cytokines. Each has a different role in the body.

This article explains what cytokines are, including the types and their role in the body.

What are cytokines?

Illustration of how cytokines work. Cytokines bind to the receptors of a target cell to signal a response.
Cytokines bind to the receptors of a target cell to signal a response. Medical Illustration by Mekhi Baldwin

Cytokines are small proteins. The body uses them to regulate immune and inflammatory responses. Some cytokines stimulate these responses, and some slow them down. 

Part of their job is to support anticancer activity in the body. Their signals tell abnormal cells to die and normal cells to live.

Another role of cytokines is to promote blood cell growth. They help all types of blood cells develop and mature.

All kinds of cells can make cytokines. However, the main producers are helper T cells and macrophages. Helper T cells are white blood cells that activate other immune system cells. Other names for them include CD4+ cells and T lymphocytes.

Macrophages are another type of white blood cell. They detect and destroy foreign invaders and activate other cells in the process.

Types of cytokines

There are several different types of cytokines, each with different roles.

Growth factors

Growth factors do just what they say—stimulate cell growth. Their role includes aiding wound healing and increasing the production of blood cell lines. They are also involved in abnormal processes, such as cancer and retinopathy (damage to blood vessels in the back of the eye).

Examples of growth factors include:

  • epidermal growth factor (EGF)
  • granulocyte-macrophage colony-stimulating factor (GM-CSF)
  • platelet-derived growth factor (PDGF)
  • vascular endothelial growth factor (VEGF)

Interferons

Interferons are cytokines that are important for fighting viruses. They activate natural killer cells and macrophages. They also have a role in suppressing tumors.

The interferons include:

  • interferon-alpha
  • interferon-beta
  • interferon-gamma

Interleukins

The main function of interleukins is activating inflammatory and immune responses. This group is large and has dozens of members. Some of the more well-known ones help fight cancer. Abbreviated as IL, they include:

  • IL-2
  • IL-7
  • IL-12
  • IL-21

Tumor necrosis factors

Tumor necrosis factors (TNFs) also play a major role in inflammation and immune response. They activate immune cells and trigger the release of other cytokines, such as interleukins. They are also involved in abnormal immune and inflammatory conditions, such as rheumatoid arthritis.

TNFs include TNF-alpha and TNF-beta.

How do cytokines work?

Cytokines work as messengers between cells. It starts when a cell that makes cytokines encounters something that stimulates it. This is usually some type of antigen. The cell releases the cytokines, which can act in three ways:

  • autocrine, or acting on the same cell
  • paracrine, or acting on nearby cells
  • endocrine, or acting on distant cells

Most of the time, the cytokines work on the same cell that released it or on nearby cells. The cytokine acts on cells by attaching to receptors. Once it binds to the receptor, it activates a response in that cell. The effect will depend on the kind of cell to which the cytokine binds.

What is cytokine release syndrome?

Cytokine release syndrome, or cytokine storm, is a severe immune system reaction that can be fatal. It is a massive production of cytokines that happens very fast. It can occur as the body responds to infection, autoimmune conditions, and some immunotherapies. 

A cytokine storm causes dangerous inflammation and other reactions. It can progress to life threatening organ failure involving multiple organ systems. Doctors treat it with supportive care and medications to decrease the immune response.

How is cytokine inflammatory response regulated?

There are several ways the body regulates cytokines. First, they have a short half-life, so they do not last very long. Their brief existence means they do not often affect cells far away from them. Most of their actions remain local in nearby cells.

The body also has a negative feedback loop for cytokines. This means high levels of cytokines should shut down the production of more cytokines. It is a way for the body to prevent the overproduction of cytokines. In a cytokine storm, the feedback loop fails, and cytokine production overwhelms the system.

In addition, some cytokines function as cytokine inhibitors. For example, IL-18 acts to inhibit other pro-inflammatory cytokines. Research also finds that the substance hemin decreases pro-inflammatory cytokines.

Food’s effect on inflammation

Foods can affect inflammation. Some foods promote inflammation, and others reduce it.

Foods that fight inflammation are generally high in antioxidants and polyphenols. Foods that may potentially decrease inflammation include:

  • coffee
  • fatty fish, such as salmon and mackerel, which are high in omega fatty acids
  • fruits, such as blueberries and cherries
  • green, leafy vegetables
  • nuts
  • olive oil
  • tomatoes

Including these foods in your diet may also help prevent chronic diseases, such as type 2 diabetes and heart disease.

Avoid foods that can promote inflammation, such as fried foods, refined carbohydrates, and red meats.  

Summary

Cytokines are messengers your body uses to regulate inflammatory and immune responses. There are several different types of cytokines with different jobs. Some of them work to inhibit other cytokines. This is one way the body regulates the effects of cytokines.

The process works to keep things in equilibrium. In certain situations, an irregular process results in a cytokine storm. Treating a cytokine storm involves tamping down the cytokine response and relieving symptoms.

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Medical Reviewer: Angelica Balingit, MD
Last Review Date: 2022 Jun 29
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