Interferon (IFN) is a type of protein called a cytokine that is secreted by cells of the body during an infection. It can inhibit viruses from spreading to neighboring cells and it can aid in destroying cancerous cells. Interferon therapy takes advantage of these natural protective properties. Commercial interferon is used as a treatment for viral infections, such as hepatitis C, and as a treatment for certain cancers.
There are different types of interferon, namely IFN-alpha, IFN-beta, and IFN-gamma. Each type binds to a different surface receptor on the cell. IFN-alpha is the type most widely used in interferon therapy. It is used to treat hepatitis C, leukemia, lymphomas, and recurrent melanoma.
Interferon-alpha has many effects on the cells in the body. When a virus has infected cells in a tissue or organ, interferon protects neighboring uninfected cells and halts the spread of the virus. Interferon therapy stimulates the release of enzymes that interfere with protein synthesis and thereby destroys virus-infected cells. Generally, interferon-alpha is one choice of treatment for patients infected with hepatitis C. It can be used in combination with other medications, such as the antiviral drug ribavirin, to improve the response to hepatitis C.
Another effect of IFN-alpha is to boost the immune system to fight off the spread of cancer in the body. Different cell types in the body, namely natural killer cells (NK cells) or macrophages, are activated by interferon and can then attack and destroy cancer cells. Interferon also increases expression of proteins on the surface of tumor cells, thereby making them more visible for attack by cells of the immune system.
Interferon therapy is used to treat patients suffering from malignant melanoma that has spread to lymph nodes. It has been shown to reduce the rate of recurrence in patients with melanoma. Interferon can also be used to treat other cancers, mainly leukemia and lymphoma.
A physician must administer interferon to a patient and it can be given as an injection in the muscle, under the skin, or in the vein. Interferon therapy does have several side effects that a patient needs to be aware of. The patient can often develop fever, chills, and flu-like symptoms. Fatigue, headache, and muscle pain may also occur. If these side effects are too severe, the patient may have to discontinue treatment with interferon.
One formulation of IFN-alpha that is used in interferon therapy contains the molecule polyethylene glycol. This molecule prevents rapid breakdown of interferon in the body and allows for the injection to be given once a week instead of the standard dose of three times a week. Increasing the interval between treatments may reduce the side effects, as well.
