interleukin
Meaning of interleukin: The short-range chemical messages that immune cells send one another in order to coordinate a response.
Definition of interleukin
An interleukin is a signaling protein released by white blood cells and by other cells to instruct the immune system. Each one tells nearby cells to multiply, to mature, to move toward an infection, or to calm down again. They are numbered in the order they were discovered, starting with interleukin-1, and more than thirty are recognized.
How do they work?
An interleukin is released, travels a short distance, and binds a matching receptor on a nearby cell. That binding changes which genes the receiving cell switches on. The range is deliberately short, so the message stays local rather than putting the whole body on alert. Effects overlap heavily: several different interleukins produce similar results, and one interleukin often does different things depending on which cell receives it. That redundancy makes the system robust and makes any single message hard to study in isolation. An interleukin is one kind of cytokine, the broader family of signaling proteins that also takes in interferons and growth factors.
What do individual ones do?
| Interleukin | Broad role |
|---|---|
| Interleukin-1 | Triggers inflammation and fever |
| Interleukin-2 | Drives T cells to multiply |
| Interleukin-6 | Prompts the liver to make inflammatory proteins |
| Interleukin-10 | Damps inflammation down |
Interleukin-6 shows how one message can be both useful and harmful. It mobilizes defenses during infection, and it also drives the joint damage of rheumatoid arthritis and much of the illness seen in a severe inflammatory response.
Why do they matter in treatment?
They are both targets and treatments. Drugs blocking an interleukin or its receptor are established in rheumatoid arthritis, psoriasis, inflammatory bowel disease and severe asthma, and silencing one message can settle a disease that resisted broader immune suppression. Interleukins can also be given as drugs, and interleukin-2 has been used to stimulate the immune system against certain cancers, at amounts that bring severe side effects. The same signals cause harm at scale: a sudden flood of them after some immune therapies produces cytokine release syndrome, with fever, low blood pressure and failing organs.
Why the name?
The word was chosen to mean a signal passing between white blood cells, which is what the first examples appeared to do. The name has outlived its accuracy. Interleukins are made by many cell types besides leukocytes, and they act on tissues far outside the immune system, including bone, liver and brain.
Also known as
Used in a sentence
Interleukin levels were measured as part of the assessment of systemic inflammation.
Good to know
The name is historical, since interleukins are made by many cell types besides white blood cells and act on tissues well beyond the immune system.
Word origin
Where “interleukin” comes from
From the Latin inter, meaning between, and the Greek leukos, meaning white, because the first examples seemed to pass only between white blood cells.