Interferons (IFNs) are a group of signaling proteins synthesized and released by host cells in response to pathogens, such as viruses, bacteria, parasites, or tumor cells. In general, virus-infected cells release interferons that cause surrounding cells to increase their antiviral defenses. Based on receptor type, human interferons can be categorized into 3 major types: type I interferons, including IFN-α, IFN-β, IFN-ε, IFN-κ, and IFN-ω, type II interferons (known as IFN-γ in humans), and type III interferons.The IFN-α protein is produced by leukocytes, which are primarily involved in innate immunity in response to viral infection. Studies have shown that enhanced expression of IFN-α in tumor-infiltrating macrophages elicits more potent dendritic cell activation and immune effector cytotoxicity.IFN-α acts as a thermogenic factor that can cause fever by altering the activity of heat-sensitive neurons in the hypothalamus. Using a similar mechanism, IFN-α can be used to reduce pain and interact with μ-opioid receptors to act as an analgesic.