Description
At least 23 different variants of IFN-alpha are known. The individual proteins have molecular masses between 19-26kD and consist of proteins with lengths of 156-166 and 172 amino acids. All IFN-alpha subtypes possess a common conserved sequence region between amino acid positions 115-151 while the amino-terminal ends are variable. Many IFN-alpha subtypes differ in their sequences at only one or two positions. Naturally occurring variants also include proteins truncated by 10 amino acids at the carboxy-terminal end. Interferons (IFNs) appear early after viral infection locally and systematically to limit spread of viral infection. They also affect cell differentiation, growth, surface antigen expression and immunoregulation. There are three naturally occurring interferons: alpha, beta and gamma. Interferon alpha (IFN-alpha, IFNa) is also known as leukocyte interferon. B-lymphocytes are the predominant cellular producers of INF-alpha. IFN-alpha is derived from lymphoblastic tissue. IFN-alpha comprises a family of related, homologous proteins, each exhibiting a unique activity profile. The activities of the different IFN-alpha species on viruses can vary twenty fold or more. INF-alpha has a number of therapeutic applications in the treatment of various human cancers and diseases of viral origin