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1. The type I Interferons consists of 14 different alpha isoforms (subtypes with slightly different specificities), a single beta, omega, epsilon and kappa isoform. Homologous molecules are found in many species, including rats and mice (in most mammals)and have been identified in birds, reptiles and fish species. In addition to these IFNs, Limitin in mice , IFN Tau in ruminants and IFN delta in pigs have been identified. All type I IFNs bind to a specific cell surface receptor complex known as IFNAR consisting of IFNAR1 and IFNAR2 . These receptors are involved in IFN signaling and the JAK-STAT signaling pathway is one of the well characterised IFN signaling pathways.

2. The type II interferons consists of interferon gamma.

3. The recently discovered 3rd class consists of interferon lambda with 3 different isoforms.

Interferon alpha and beta are produced by many cell types, including T-cells and B-cells, and are an imporant component of the anti- viral response. They stimulate both macrophages and NK cells. Interferons alpha and beta are also active against tumors.

Interferon was scarce and expensive until 1980 when the Interferon gene was inserted into bacteria using genetic engineering, allowing mass cultivation and purification from bacterial cultures. Several different types of interferon are now approved for use in humans, and interferon therapy is now used (in combination with chemotheraphy and radiation) as a treatment for many types of systemic cancer. Unfortunately, interferon delivered intravenously is not very effective, and often causes undesirable side effects at high doses.

Interferon-alpha was cleared by the United States Food and Drug Administration (FDA) in February 25February 25 is the 56th day of the year in the Gregorian Calendar. There are 309 days remaining, 310 in leap years. Events 138 The Emperor Hadrian adopts Antoninus Pius, effectively making him his successor. 1570 Pope Pius V excommunicates Queen Elizabeth 19911991 like 2002, is a palindromic year. It also has the same calendar as 2002, including Easter on March 31. It is a common year starting on Tuesday. Events January January 2 Sharon Pratt Dixon is sworn in as mayor of Washington, DC becoming the first blac as a treatment for hepatitis CHepatitis C is a form of hepatitis ( liver inflammation) caused by a virus, the Hepatitis C virus (HCV). Before the virus was discovered, in 1989, the syndrome was initially referred to as a "non-A-non-B hepatitis". Symptoms In most cases, acute hepatitis. Several different forms of interferon alpha, including interferon alpha-2a, interferon alpha-2b, and interferon alfacon-1 are approved for the treatment of viral hepatitis.

Interferon beta is used in the treatment and control of the neurological disorder multiple sclerosisMultiple sclerosis MS is a demyelinating disease, a non-contagious chronic autoimmune disorder of the central nervous system which can present with a variety of neurological symptoms occurring in attacks or slowly progressing over time. It has no cure yet.Interferon beta also plays a major role in septic shockSeptic shock is a serious medical condition causing such effects as multiple organ failure and death in response to infection and sepsis. Its most common victims are children and the elderly, as their immune systems cannot cope with the infection as well.

About half of hepatitis CHepatitis C is a form of hepatitis ( liver inflammation) caused by a virus, the Hepatitis C virus (HCV). Before the virus was discovered, in 1989, the syndrome was initially referred to as a "non-A-non-B hepatitis". Symptoms In most cases, acute hepatitis patients treated with interferon respond, with better blood tests and better liver biopsies. Half the patients who respond relapse once the interferon is stopped, for a total cure rate of about 25%. There is some evidence that giving interferon immediately following infection can prevent hepatitis C; unfortunately, people infected by hepatitis C often do not display symptoms until months or years later.

More recently, the FDA approved pegylated interferon-alpha, in which polyethylene glycol is added to make the interferon last longer in the body. (Pegylated interferon-alpha-2b was approved in January 2001; pegylated interferon-alpha-2a was appoved in October 2002.) The pegylated form is injected once weekly, rather than three times per week for conventional interferon-alpha. Used in combination with the antiviral drug ribavirin, pegylated interferon produces sustained cure rates of 75% or better in people with genotype 2 or 3 hepatitis C (which is easier to treat) and about 50% in people with genotype 1 (which is most common in the U.S. and Western Europe).

Interferon-gamma is involved in the regulation of the immune and inflammatory responses; in humans, there is only one type of interferon-gamma. Interferon-gamma has had some anti-viral and anti-tumor effects, but these are generally weak; however, interferon-gamma potentiates the effects of interferon-alpha and interferon-beta. Unfortunately, interferon-gamma needs to be released at the site of a tumor in very small doses; at this time, interferon-gamma is not very useful for treating cancer.

Inteferon-gamma is also released by Th1 cells, and recruits leukocytes to a site of infection, resulting in increased inflammation. It also stimulates macrophages to kill bacteria that have been engulfed. The interferon-gamma released by Th1 cells is also important in regulating the Th2 response.

Interferon-omega is released by leukocytes at the site of viral infection or tumors.

See also: ImmunotherapyImmunotherapy is a disease treatment based upon the concept of triggering the body's own natural defenses to fight off the disease, usually by stimulating the immune system either locally or systemically. Oncology represents one of the most actively resea