Interferons (IFN) are cytokines released by the body in response to viral infections and neoplasia. They are classified according to cellular origin and the type of receptor they bind to. IFN-alpha and IFN-beta bind to type 1 receptors whilst IFN-gamma binds only to type 2 receptors.

Interferon-alpha

• produced by leucocytes
• antiviral action
• useful in hepatitis B & C, Kaposi's sarcoma, metastatic renal cell cancer, hairy cell leukaemia
• adverse effects include flu-like symptoms and depression

Interferon-beta

• produced by fibroblasts
• antiviral action
• reduces the frequency of exacerbations in patients with relapsing-remitting MS

Interferon-gamma

• predominately natural killer cells. Also by T helper cells
• weaker antiviral action, more of a role in immunomodulation particularly macrophage activation
• may be useful in chronic granulomatous disease and osteopetrosis