Cytokines Explained

What they are

Cleveland Clinic describes cytokines as proteins that function as chemical messengers in the immune system, signaling immune cells to fight invaders, and also sending signals that keep the immune system functioning when there is no threat. [1] MedlinePlus notes that T lymphocytes release cytokines which help control the immune response. [2] Most cytokines are released by immune cells such as macrophages, dendritic cells, lymphocytes and neutrophils, but many other cells can release them too, including cells lining blood vessels and organs and connective-tissue cells. [1]

Main families

How the message is delivered

A cytokine binds to a matching receptor on a receiving cell, like a key in a lock, and the cell acts on the message. [1] Signals can act on the cell that released it, on nearby cells, or on distant cells. [1] Cytokines are often described as "pro-inflammatory" (they trigger or heighten inflammation) or "anti-inflammatory" (they stop or lessen it). [1] Stopping inflammation is as important as starting it. [1] These labels describe direction of effect. They do not make a cytokine "good" or "bad" to have more of, so "raise the good ones, lower the bad ones" is not something these sources support. See claim check: boosting immunity.

When cytokine signaling becomes harmful

Cytokine release syndrome (CRS), sometimes called a cytokine storm, is an excessive release of cytokines that can affect many body systems and can be life-threatening without treatment. [1] In cancer immunotherapy, a review reports that in up to one-third of patients with engineered T-cell therapies, significant toxicities occur that are directly associated with powerful immune effector responses, most often CRS and a neurologic syndrome. [3] CRS is a medical emergency managed by specialist teams. Call 911 (US) or your local emergency number for a severe reaction after any immune-based treatment.

Blocking one cytokine: what trials found

The real-world test of the idea "this cytokine drives harm" is a randomized trial of a drug that blocks it.

• Interleukin-1 beta, heart disease. In the CANTOS trial of 10,061 people with a previous heart attack and elevated CRP, the 150 mg dose of the IL-1 beta blocker canakinumab lowered recurrent cardiovascular events (hazard ratio 0.85, 95% CI 0.74 to 0.98), while fatal infections were more common than with placebo. [4]
• Interleukin-6, hospitalized COVID-19. A Cochrane living review of 32 trials with 12,160 hospitalized participants found tocilizumab reduces all-cause mortality at day 28 (risk ratio 0.88, 95% CI 0.81 to 0.94, high-certainty evidence) but probably results in little or no increase in clinical improvement at day 28 (risk ratio 1.05, 95% CI 1.00 to 1.11, moderate certainty). For sarilumab, the effect on mortality was very uncertain. [5]

These were prescription antibodies tested in specific, closely followed patient groups. They do not show that supplements, foods or devices advertised as "balancing cytokines" do anything comparable. Non-drug claims need their own human outcome data. See claim check: reduces inflammation means improves health.

Cytokine tests

A cytokine panel is a blood test that checks cytokine levels. [1] Cleveland Clinic says elevated levels may be a sign of heightened inflammation. [1] A panel result is a biomarker and is not a diagnosis or a measure of overall immune strength. Consumer panels sold without a clinical question are discussed in unvalidated immune panels.

Evidence labels: the definitions are established. The two drug examples are trial-tested prescription uses in specific groups (the CANTOS result is mixed: benefit at one dose, more fatal infections). Regulatory status was not verified for any country on this page, so check the regulator for current labels. Claims that a supplement "regulates cytokines" are marketing claims unless a human trial with clinical outcomes exists.