Description: IFN alpha 4 is a type I interferon, previously known as B-cell interferon, leukocyte interferon, lymphoblast interferon, and pH2-stable interferon. IFN alpha 4 is one of at least 23 different known variants of IFN alpha. The individual proteins have molecular masses between 19-26 kDa and consist of proteins with lengths of 156-166 and 172 amino acids. IFN alpha forms are produced by monocytes/macrophages, lymphoblastoid cells, fibroblasts, and a number of different cell types following induction by viruses, nucleic acids, glucocorticoid hormones, and low-molecular weight substances (n-butyrate, 5-bromodeoxyuridine). IFN alpha4 demonstrates antiviral, antiparasitic,and antiproliferative activities.