How Does TNF Cause Inflammation?

If you have an immune system disease like rheumatoid arthritis (RA), you may have heard your doctor use the term TNF. It’s shorthand for tumor necrosis factor, a substance in your body that causes inflammation, or swelling.

It may surprise you to learn that inflammation can be a good thing. It happens when your immune system -- your body’s natural defense force -- is fighting a possible threat. For example, when you have a cold, your sinuses swell. When you get a cut, your finger turns warm and red. These things don’t feel good, but they show your immune system is doing its job.

Sometimes, inflammation isn’t good for the body. If you have a disease like RA or psoriatic arthritis, your immune system is confused about what to attack. It goes after healthy body parts, like your joints, by mistake. Your system gets flooded with inflammation, which often means you have too much TNF -- specifically, a type called TNF alpha.

Inflammation Is a Chain Reaction

When you have an infection, certain white blood cells release key chemicals that tell other cells to cause inflammation. Your doctor might call them signaling chemicals. TNF is a major player when it comes to inflammation.

Think of the white blood cells that produce TNF as the army. TNF is the signal that tells the rest of the defense units to come to the right place and what to do.

What do these defense units do? Some white blood cells fight off infection. TNF also tells other cells to make other chemicals, like the hormones that cause you to lose your appetite when you’re sick. It’s all part of the inflammatory process.

Signs of High TNF

If you have a severe bacterial infection, like a bad cold or pneumonia, high TNF levels are a sign of inflammation that’s helping you heal. But high TNF levels can also trigger some unpleasant symptoms:

If you have a lot of TNF but no infection, your immune system may not be working properly. Symptoms are usually different from when you have an infection. If you have psoriasis, high TNF levels play a role in the raised, red skin plaques that come with the disease. For people with RA, they play a role in joint swelling and redness, aka joint inflammation.


When TNF Causes Too Much Inflammation

Having the right balance of TNF in your body is important. If you’re healthy, your body naturally takes care of this balance: It blocks any extra TNF you might have. That doesn’t always happen in diseases like RA, so you end up with too much TNF in your blood. That leads to inflammation and painful symptoms.

Fortunately, there are drugs that block excess TNF. They’re part of a group called biologics, and you might hear your doctor call them one of these names:

  • TNF inhibitors
  • Anti-TNF agents
  • Anti-TNF drugs
  • TNF blockers

These drugs stop TNF’s “create inflammation now” message before it can get to other cells. The result is less inflammation in your joints, digestive tract, or skin, depending on what disease you have.

WebMD Medical Reference Reviewed by Laura J. Martin, MD on April 23, 2017


American College of Rheumatology: “TNF Inhibitors.”

Institute for Quality and Efficiency in Health Care: “What Is An Inflammation?”

Arthritis Research UK: “The Science Behind the Success of Anti-TNF Therapy.”

Arundathi Jayatilleke, MD, assistant professor, department of medicine, division of rheumatology, Drexel University College of Medicine, Philadelphia.

The Oncologist: “The Molecular Perspective: Tumor Necrosis Factor.”

UpToDate: “Patient education: Rheumatoid arthritis treatment (Beyond the Basics).”

FDA: “Information on Tumor (TNF) Blockers (marketed as Remicade, Enbrel, Humira, Cimzia, and Simponi).”

JAMA: “Non–TNF-Targeted Biologic vs a Second Anti-TNF Drug to Treat Rheumatoid Arthritis in Patients With Insufficient Response to a First Anti-TNF Drug: A Randomized Clinical Trial.”

Arthritis Foundation: “Biologics Overview.”

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