Interferon alpha (IFN-α) is a 21.5 kDa cytokine belonging to the type I interferon family, crucial for innate immunity and antiviral defense mechanisms. There are multiple subtypes of IFN-α, each encoded by a distinct gene. In humans, the IFN-α family consists of at least 13 subtypes, including IFN-α1, IFN-α2, IFN-α4, IFN-α5, IFN-α6, IFN-α7, IFN-α8, IFN-α10, IFN-α14, IFN-α16, IFN-α17, and IFN-α21 (more variants have been reported). Typically produced by leukocytes, IFN-α plays an important role in modulating the body’s response against viral infections and tumor cells.

Upon secretion, IFN-α binds to the IFN-α/β, initiating a cascade of signaling events that lead to the expression of interferon-stimulated genes (ISGs). These ISGs encode proteins that inhibit viral replication, enhance the immune system’s ability to detect infected cells, and activate immune cells like natural killer cells and macrophages. Physiologically, IFN-α is vital in the innate immune response, providing an early defense mechanism against viral infections.

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