British researchers are hoping to harness the body's natural killer cells to fight cancer.

The immune cells produce chemicals that destroy foreign invaders and rogue leukaemia cells.

Scientists at London's Royal Free Hospital believe an infusion of the cells from a donor could help leukaemia patients.

They are trying to find a way to treat sufferers of acute myeloid leukaemia (AML) who relapse after treatment and do not have a suitable match for a bone marrow transplant.

About 2,000 new cases of AML are diagnosed every year in the UK.

Almost three-quarters of patients achieve complete remission of the disease after chemotherapy treatment.

However, the majority of elderly patients and more than half the young sufferers die after suffering a relapse.

Immune therapy

The new research is based on a technique to filter natural killer cells from donated blood.

The team aims to grow the cells in the laboratory and use them as a therapy.

A clinical trial could take place within two years, said the Royal Free's Dr Mark Lowdell.

He told BBC News Online: "If this very novel treatment works, every patient with AML would be eligible for immune therapy of their disease."

The research is backed by the Leukaemia Research Fund. Its scientific director Dr David Grant said the work had grown out of a new understanding of how our immune system reacts to cancer cells

"We are confident this technique will prove to be a new weapon in the fight against leukaemia, and eventually help to save the lives of patients," he said.