Limitin was first isolated from cells of bone marrow responsible for regulating blood cell development. Instead of promoting blood cell growth, limitin was actively suppressive. Kenji Oritani, M.D., Ph.D., now an Assistant Professor at Osaka University, began a search for the gene encoding limitin during Postdoctoral studies in Oklahoma. One third of the limitin sequence resembles interferons, and limitin works through an interferon receptor on cells. The human counterpart of limitin is now being sought with the hope that it will be beneficial as a drug.
Interferons play important roles in the normal immune system.
They are approved by the U.S. Food and Drug Administration for treatment of certain types of cancer, that include leukemia, melanoma, chronic myeloid leukemia and AIDS-related sarcoma. While the previously known interferons are also valuable as drugs for viral hepatitis and multiple sclerosis, there are many negative side effects. For example, interferon treated patients may experience flu-like symptoms, fatigue, autoimmune reactions and depression. Limitin would be beneficial as a drug if it had fewer undesirable reactions than interferons. Several years will be required to learn the full range of responses by various normal cell types and tumors to limitin.