Intron A — a therapeutic focus

Anti-viral Introduction Originally identified as anti-viral agents, interferons are now widely regarded as being major growth regulators and modifiers of the immune response. Interferons are divided into two classes by their receptor binding properties type 1 (alpha and beta) and type 2 (gamma). The alpha interferon family is also polygenic. The physiological relevance of the large number of proteins which act on the type 1 receptor is not known. Table 1 summarises the properties of type 1 interferons, along with their therapeutic applications. These interferons were the first biological agents to be available in therapeutic amounts initially from cell culture and later from recombinant DNA technology. As the pioneers of cytokine therapy they have been sent along false and dead-end trails, but evidence of the extent of their therapeutic usefulness is still accumulating. Initially side-effects such as pyrexia, flu-like symptoms and bone-marrow depression were found at high doses, but worries that these side-effects would make effective interferon dosing impossible have not been realised.