Cancer sufferers could be cured with injections of immune cells from other people within two years, scientists say.
US researchers have been given the go-ahead to give patients transfusions of "super strength" cancer-killing cells from donors.
Dr Zheng Cui, of the Wake Forest University School of Medicine, has shown in laboratory experiments that immune cells from some people can be almost 50 times more effective in fighting cancer than in others.
Dr Cui, whose work is highlighted in this week's New Scientist magazine, has previously shown cells from mice found to be immune to cancer can be used to cure ordinary mice with tumours.
The work raises the prospect of using cancer-killing immune system cells called granulocytes from donors to significantly boost a cancer patient's ability to fight their disease, and potentially cure them.
Last Mod: 20 Eylül 2007, 14:19
The US Food and Drug Administration (FDA) last week gave Dr Cui permission to inject super-strength granulocytes into 22 patients.
Dr Cui said: "Our hope is that this could be a cure. Our pre-clinical tests have been exceptionally successful.
"If this is half as effective in humans as it is in mice it could be that half of patients could be cured or at least given one to two years extra of high quality life.
"The technology needed to do this already exists, so if it works in humans we could save a lot of lives, and we could be doing so within two years."
Dr Cui is confident patients could benefit from the technique quickly because the technology used to extract granulocytes is the same as that already used by hospitals to obtain other blood components such as plasma or platelets.
Prof Gribben, a cancer immunologist at Cancer Research UK's experimental centre at St Bartholomew's Hospital, London, said: "The concept of using immune system cells to kill off someone else's cancer is very, very exciting."
Dr Cui, who presented his latest findings at an anti-ageing conference in Cambridge last week, extracted granulocytes from 100 people, including some with cancer.
When the immune cells were mixed with cervical cancer cells, those from different individuals demonstrated vastly varying abilities to fight the cancer.
Those of the strongest participants killed close to 97 per cent of the cancer cells in 24 hours, while those of the weakest killed only two per cent.
The abilities of the cells of participants aged over 50 were lower than average, and those of cancer patients even lower.
Dr Cui noticed that the strength of a person's immune system to combat cancer can also vary according to how stressed they are and the time of year.
Initial experiments suggest it may be possible to transfer granulocytes which have demonstrated strong cancer-fighting powers into cancer sufferers.
In 1999 Prof Cui and colleagues discovered a male mouse that appeared to be completely resistant to virulent cancer cells of several different types.
Since then more than 2000 mice in 15 generations have been bred from the original cancer-free mouse and 40 per cent of the offspring have inherited the immunity.
With the immune system, some types of cells which provide "innate immunity" are constantly on patrol for foreign invaders, while others have to firstly learn to identify a specific threat before going on the attack.
Scientists developing cancer vaccines have generally attempted to stimulate responses in the immune system cells that require prior exposure.
Last year Dr Cui caused shockwaves in the cancer research community when he identified granulocytes as the cells responsible for the mouse cancer immunity – because they are among those which act automatically.
Prof Gribben said: "This is surprising because it goes against how we thought immune system works against cancer. It makes us think again about our preconceived notions."
Prof Cui injected granulocytes from immune mice into ordinary mice, and found it was possible to give them protection from cancer.
Even more excitingly he found the transfusions caused existing cancers to go into remission and to clear them completely within weeks.
A single dose of the cells appeared to give many of the mice resistance to cancer for the rest of their lives.
Granulocyte transfusion has previously been used to try to prevent infections in cancer patients whose immune systems have been weakened by chemotherapy.
However their effectiveness has been unclear because they have mainly been given to patients in an advanced stage of disease.
Prof Gribben warned the US researchers would have to be careful to avoid other immune system cells from the donor proliferating in the patient's body.
He added: "If they're using live cells there is a theoretical risk of graft-versus-host disease, which can prove fatal."
Dr Cui said he is working on ways to minimise this risk.