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Immune cells from 鈥渃ancer-resistant鈥� people are to be injected into those with cancer to help fight the disease.

Zheng Cui at Wake Forest University of Medicine in Winston-Salem, North Carolina, and his colleagues have received permission from the US Food and Drug Administration (FDA) to screen people for their ability to ward off cancer. Immune cells from the best cancer fighters will be given to cancer patients, after being matched for blood type.

All of us have some ability to fight cancer, via immune cells called NK cells which can identify and kill tumour cells, although the extent of these cells鈥� influence is not known. But Cui has now discovered that a much larger population of immune cells called granulocytes can also kill cancer and that the effectiveness of these cells varies from person to person.

Cui took blood samples from more than 100 people and mixed their granulocytes with cervical cancer cells. While granulocytes from one individual killed around 97 per cent of cancer cells within 24 hours, those from another healthy individual only killed around 2 per cent of cancer cells. Average cancer-killing ability appeared to be lower in adults over the age of 50 and even lower in people with cancer. It also fell when people were stressed, and at certain times of the year. 鈥淣obody seems to have any cancer-killing ability during the winter months from November to April,鈥� says Cui, who presented at the Strategies for Engineered Negligible Senescence meeting in Cambridge, UK, earlier this month.

鈥淎ll people possess some cancer-fighting ability, though it is lower when people are stressed and at certain times of the year鈥�

Initial evidence suggests it may be possible to transfer the ability to fight off cancer between people. Granulocytes are already taken from donors and given to some patients whose immune systems have been depleted by chemotherapy, for example, though not to treat cancer directly. And last year Cui successfully treated a range of different cancers in mice by injecting them with granulocytes from a strain of mice that are completely resistant to cancer (Proceedings of the National Academy of Sciences, ).

Cui hopes to begin human trials next summer in the US, when the immune systems of potential granulocyte donors will be at their peak.

鈥淭he concept of using immune cells from one person to fight cancer in another person is a very hot topic right now,鈥� says John Gribben, a cancer immunologist at Cancer Research UK鈥檚 experimental medicine centre at St Bartholomew鈥檚 Hospital, London.

However, if Cui plans to try this therapy in people, he will have to be very careful, Gribben says. 鈥淚f they鈥檙e using live cells there is a theoretical risk of graft-versus-host disease, which can prove fatal.鈥� This is a particular problem in patients with depleted immune systems, where transfused cells may proliferate and take over the host鈥檚 immune system, eventually destroying cells in the bone marrow. Cui says he is working with the FDA to minimise this risk.