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Problems with immortality

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Immortality can be fatal, says Alison Sinclair of BIOLS. Living cells which continue beyond their normal life span, and multiply without check, disrupt the delicate co-existence on which our life depends. This co-existence requires an orderly mortality of body cells; disorder leads to cancer.

Some viruses cause body cells to become immortal and therefore potentially cancerous. One of these is the Epstein-Barr virus, which most of us carry but which can cause cancer in some people; for example it can cause Hodgkin's disease, which affects more than a thousand people in this country alone, and Burkitt's Lymphoma, which is a problem in Africa. Alison is working on Epstein-Barr virus because its mode of action raises fundamental questions about normal controls in the living body: about life, death and proliferation. Her research is supported by the Leukaemia Research Fund.

Epstein-Barr virus affects the white blood cells which play a vital part in our immune system. These cells usually have a finite life and do not divide unless they receive an appropriate signal. The virus seems to switch off the effect of a natural control protein, which normally prevents unwanted cell division. Therefore the virus creates immortal cell lines which, in cell culture, continue and multiply, carrying the virus with them. Usually, in a healthy body, the effects of the virus are kept under control by the immune system. If the immune system is suppressed, however, for example by the effects of another disease (malaria, in the case of Burkitt's Lymphoma), the immortal cell lines can run destructively rampant.

Viruses also play a key role in the development of a variety of other cancers, including most genital cancers, liver cancer, and Kaposi's Sarcoma. According to Alison, the virus is only one factor in the development of the cancer; various other co-factors, such as carcinogens, are also very important. Understanding the way in which these viruses and other factors interact with the cellular control mechanisms should lead to better methods of treatment.

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March 7th 1997