The impact of molecular biology on the practice of medicine has been particularly evident in hematology. The technology that has made it possible to determine the fine structure of genes has not only increased our understanding of basic regulatory processes, but has also made possible therapeutic and diagnostic feats that previously were out of reach.
Using the techniques of molecular biology, sufficient quantities of biologically active proteins have been synthesized to treat patients with certain hematologic disorders. One product, interferon alfa, found to be effective in the treatment of hairy-cell leukemia1,2 and chronic granulocytic leukemia,3 is already commercially available in the United States. Others, including tissue plasminogen activator, erythropoietin (EPO),4,5 and interleukin 2, have already undergone extensive clinical trials and may soon be generally available. In the case of other mediators, such as tumor necrosis factor/cachectin, granulocyte-monocyte colony stimulating factor, granulocyte stimulating factor, macrophage stimulating factor, and