Immune to cancer -- for life

Researchers Zheng Cui and Mark Willingham, and a team of eight others, have discovered a strain of mice that are immune to cancer. When cancer cells are injected into the mice, they are destroyed. But even better, mice that have established tumors are completely cured by injections of white blood cells from the cancer resistant strain.

Highly aggressive cancers and very large tumors were eradicated when the white blood cells from the mutant mice were injected into normal mice. And the normal mice were then protected from future cancers, even normally lethal doses of injected cancer cells.

The immunity is inherited in the mutant strain, and the pattern of inheritance indicates that it is caused by a single mutation, as if a switch had been thrown to make the white blood cells super effective at killing cancers. This gives the researchers hope that a drug can be made to target that switch in humans.

The mechanism does not involve T-cells, the cells that have to be exposed to a pathogen in order to kill it. Instead, the effect is based on the innate response of macrophages, neutrophils, and natural killer cells -- cells that do not need pre-exposure to the disease.

The mutation appears to have no side-effects, and does not harm the organism.

While the trait has only been seen in mice at this point, humans have an even stronger immune response than mice, because they must live longer before they can reproduce. So the effect in humans may be correspondingly higher.