Interleukins are naturally occurring proteins produced by the body that help the body's immune system. They are not stored within the body’s cells but are secreted when stimulation, such as infection, presents itself. While dozens of interleukins and their effects have been identified, scientists believe there are many more still to be found. The different types of interleukins are responsible for triggering an assortment of infection-fighting immune responses, including pain, fever, inflammation, allergic reactions and cell regeneration.
As part of the cytokine family of cell-signaling molecules, interleukins have a major role in the immune system, but they don’t actively create the immune response. They serve instead as messengers, passing the word among cells — particularly white blood cells — to let them know their services are needed. The appropriate cells then go to work.
The role of interleukins within the immune system has led to their use in fighting some types of cancer and diseases including rheumatoid arthritis and Crohn’s disease. While the body produces a relatively small amount of interleukins, scientists have figured out how to reproduce them in laboratories, making larger quantities readily available for medicinal purposes. When administered, these high-dose interleukins trigger healthy cells to redouble their efforts in fighting cancerous cells and other threats to the body. Biological therapy using interleukins also can help rebuild an immune system practically eliminated by the sometimes harsh treatments needed to destroy cancerous tumors.
Side effects of interleukin therapy can include very low blood pressure, swelling, chills, fever, nausea and vomiting. Bruising and bleeding also can occur more easily. Side effects are usually short-lived and rarely linger once treatment ends, though the severity of the side effects can lead some patients to require hospitalization during treatment.
While interleukin therapy that boosts the immune system into overdrive can have major health benefits in some situations, an overactive immune system is believed to be the culprit behind autoimmune diseases including lupus, fibromyalgia and multiple sclerosis. Such diseases are believed to be caused by a breakdown in communication. Another part of the body’s immune system makeup — T suppressor cells — are meant to signal an end to fighting once the body has won, and interleukins are critical to getting the word out. Problems may arise, however, when the appropriate cells don’t get the interleukins’ message to stop fighting, chose to ignore the message to stop or receive a message to keep fighting because malfunctioning T cells incorrectly believe that some infection remains.