A MASTER gene that causes blood stem cells to turn into disease-fighting "natural killer" immune cells has been identified by UK researchers, according to a recent report.

The discovery could one day help scientists boost the human body's production of these frontline tumour-killing cells, creating new ways to treat cancer.

The researchers have "knocked out" the gene in question, known as E4bp4, in a mouse model, creating the world's first animal model entirely lacking natural killer cells, but with all other blood cells and immune cells intact.

According to a report of the study, published in Nature Immunology, this breakthrough should help solve the mystery of the role that natural killer (NK) cells play in auto-immune diseases, such as diabetes and multiple sclerosis.

Some scientists think that these diseases are caused by malfunctioning NK cells that turn on the body and attack healthy cells, causing disease instead of fighting it. Clarifying the role of NK cells could lead to new ways of treating these conditions.

The study was carried out by researchers at Imperial College London, University College London, and the Medical Research Council.

Natural killer cells - a type of white blood cell - are a main component of the body's innate, quick-response immune system.

They provide a fast frontline defence against tumours, viruses and bacterial infections, by scanning the body for cells that are cancerous or infected with a virus or a bacterial pathogen, and killing them.

NK cells - along with all other types of blood cell, both white and red - are continuously generated from blood stem cells in our bone marrow over the course of a person's lifetime.

The gene E4bp4 identified in the recent study is the "master gene" for NK cell production - meaning it is the primary driver that causes blood stem cells to differentiate into NK cells.

The researchers behind the study - led by Dr Hugh Brady from the Department of Life Sciences at Imperial College London - are hoping to progress with a drug treatment for cancer patients that reacts with the protein expressed by their E4bp4 gene, causing their bodies to produce a higher-than-normal number of NK cells, to increase the chances of destroying tumours.

At present, NK cells isolated from donated blood are sometimes used to treat cancer patients, but the effectiveness of donated cells is limited because NK cells can be slightly different from person to person.

Dr Brady explained: "If increased numbers of the patient's own blood stem cells could be coerced into differentiating into NK cells, via drug treatment, we would be able to bolster the body's cancer-fighting force, without having to deal with the problems of donor incompatibility."

Dr Brady and his colleagues at the Medical Research Council's National Institute for Medical Research proved the pivotal role that E4bp4 plays in NK production after they "knocked out" the gene in a mouse model. Without E4bp4, the mouse produced no NK cells - and other types of blood cell were unaffected.

As well as proving their hypothesis about the function of the E4bp4 gene, this animal model will allow medical researchers, for the first time, to discover if NK cell malfunction is behind a range of medical conditions, including auto-immune disorders, inflammatory conditions, persistent viral infections, female infertility and graft rejection.

Dr Brady said: "Since shortly after they were discovered in the 1970s, some scientists have suspected that the vital disease-fighting NK cells could be behind a number of serious medical conditions, when they malfunction.

"Now, finally, with our discovery of the NK cell master gene and subsequent creation of our mouse model, we will be able to find out if the progression of these diseases is impeded or aided by the removal of NK cells from the equation.

"This will solve the often-debated question of whether NK cells are always the ‘good guys' or, if in certain circumstances, they cause more harm than good," he added.

The researchers were initially studying the effect of E4bp4 in a very rare but fatal form of childhood leukaemia when they discovered its importance for NK cells. The study was funded by the charities Children With Leukaemia and Leukaemia Research.