Scientists were looking for the answer to the question by studying modified laboratory mice. They should have gotten brain cancer by the age of three months. These mice were exposed to asthma-causing factors. It turned out that animals with asthma did not develop brain tumors.
Scientists have found that when a human or mouse develops asthma, their T cells are activated. This can cause inflammation of the lungs, but it avoids the growth of brain tumors. Thus, T cells begin to secrete a special protein that acts on the immune cells of the microglia, blocking their activation.
This discovery could aid in the development of anti-cancer therapies.