NEW YORK — After a three-year search, researchers in Massachusetts have discovered an important human blood growth factor that some scientists thought did not exist.
The discovery of the factor, interleukin 3, solves a scientific puzzle that has persisted for several years and offers a potential new strategy for treatment of many medical conditions in which a patient`s blood production and immune defenses are seriously impaired. Cancer and AIDS could be among the targets of medical use of the newly discoered substance.
The researchers, scientists at Genetics Institute, a biotechnology company in Cambridge, Mass., report in the Oct. 10 issue of the journal Cell that they discovered the gene for the factor as well as the substance itself. This knowledge makes it possible to develop the blood growth factor in bacteria and animal cells to provide supplies for intensive study.
Clark and other scientists at the company stress that interleukin 3 is not now available for any use in humans.
Scientists are beginning studies of the factor`s effects in animals and hope to start testing it in humans. Dr. Steven Clark, a leader of the research, said his group hopes to begin clinical trials sometime late next year.
The first medical uses the scientists will test will be speeding patients` recovery from bone marrow transplants, correcting the blood-destroying side effects of radiation and chemotherapy in cancer patients and attempting to restore immune defenses in patients with acquired immune deficiency syndrome.
Dr. Robert Kamen, research vice president of Genetics Institute, said the company was concentrating on developing products to stimulate the activity of the normal blood-forming and immune defense systems. Human interleukin 3, also known as multicolony stimulating factor, was discovered in the course of this research.
Many serious illnesses result from failure of some aspect of the blood-forming and immune defense systems. These failures can occur either as a fundamental part of the disease process, as with AIDS, which destroys the body`s ability to fight disease, or as an unwanted effect of treatment, such as when anticancer drugs or radiation destroys blood and immune defense cells. The ultimate source of all cells of blood and the immune system is the bone marrow, but the way the fundamental marrow cells give rise to all of these many different specialized cells is complex and only partly understood. Much of the research toward understanding this natural process of regulation in humans began with studies in laboratory animals of how blood formation is controlled. The natural control substances that have been found have often been named colony stimulating factors because they stimulate the growth of colonies of specific cell types in the laboratory.
The best known of these factors has been interleukin 2, which is already in experimental use in cancer treatment.