Cytokines are signaling proteins that help control inflammation in your body. They allow your immune system to mount a defense if germs or other substances that can make you sick enter your body. Too many cytokines can lead to excess inflammation and conditions like autoimmune diseases.
Cytokines are proteins that function as chemical messengers in your immune system. Your immune system is a network with several parts that work together to protect your body from threats, like germs that can make you sick. It contains immune cells that fight invading pathogens (like viruses and bacteria), allergens and other harmful substances that enter your body. Cytokines signal those immune cells to fight the invaders.
Even when there’s no threat, cytokines send signals to other cells that keep your immune system functioning.
Cytokines include different types of proteins that tell immune cells where to go and what to do to keep your immune system functioning correctly.
Some cytokines get their names from the type of cell that makes them, including:
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Cytokines are most known for regulating inflammation in your body. Many people think of inflammation as a pesky symptom that means you’re sick or have allergies. But inflammation is a sign that your body’s immune cells are fighting invaders or healing tissue damage. Your body’s cells release cytokines when there’s a threat. The cytokines tell your immune cells how to fight threats and repair injuries.
Think of cytokines as chemical messengers that tell cells how to behave.
Cytokines can also signal your body’s cells to release more cytokines to increase your body’s inflammatory response.
When your body’s immune response is working correctly, cytokines trigger inflammation that helps fight threats and repair tissue. Cytokines also decrease or stop your body’s inflammatory response when you no longer need it.
Stopping your body’s inflammatory response is just as important as starting it. Too much inflammation can cause unpleasant symptoms, lead to long-term diseases and can even be life-threatening without treatment.
Certain cells release cytokines while other cells contain cytokine receptors. Think of a cytokine as a key and the receptor on the receiving cell like a lock. When the cytokine (key) enters the cytokine receptor (lock), the receiving cell receives a message that tells it what to do. The cell acts based on the message it receives.
For example, an immune cell may detect a harmful substance in your body, like a virus, and release cytokines in response. Cytokines can travel through your bloodstream or directly into tissue until they reach a cell with the matching receptor. Once the cytokine binds to the receptor, the receiving cell receives instructions and acts on them. For instance, the cell may travel to the virus and attack it. It may increase its defenses to prevent viruses from invading.
Cytokines may signal cells close to the cell that released them, or they can travel great distances to relay their message.
Cells with cytokine receptors are located throughout your body. In fact, most of your body’s organs contain cells with cytokine receptors. Having cells with cytokine receptors throughout your body allows inflammation to occur in widespread locations.
The cells that make up your immune system, or immune cells, release most of your body’s cytokines. Still, many cells throughout your body — not just immune cells — can release cytokines.
Immune cells include your body’s white blood cells, also called leukocytes. Immune cells that release cytokines include:
Cells that aren’t considered immune cells that also release cytokines include:
Various cells can release the same kind of cytokine.
Cytokines are so essential to your immune system that they play a role in most conditions and diseases that may affect you. Typically, cytokines help keep you infection-free. If your immune system releases too many cytokines — in response to an infection or treatments like immunotherapy — you may develop cytokine release syndrome (CRS), also called a cytokine storm. You may develop various symptoms that affect multiple body systems. CRS can be life-threatening without treatment. Too many cytokines can create a heightened inflammatory response. Too much inflammation can damage tissue and lead to diseases and conditions, including:
Your healthcare provider can prescribe treatments to help reduce inflammation if you have too many cytokines and an overactive immune response.
Healthcare providers can determine if your body is producing too many or too few cytokines by using a cytokine panel. A cytokine panel is a blood test that checks your cytokine levels. A healthcare provider draws a blood sample and tests it for cytokines associated with inflammation. Elevated cytokines may be a sign of heightened inflammation, and you may need medication to help.
A note from Cleveland Clinic
Cytokines are essential to having a healthy immune system. As with many things, moderation is key. Having the right amount of cytokines, signaling correctly, can keep you infection-free. High levels of cytokines may lead to excessive inflammation that can be harmful without treatment.
Last reviewed by a Cleveland Clinic medical professional on 01/03/2023.
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