Your immune system is like your body’s personal security team. Its job is to protect you from germs like viruses and bacteria. Most of the time, it does this very well. But sometimes, things go wrong.
A new study from the Garvan Institute of Medical Research in Australia shows that certain changes in our genes can make immune cells turn against the body, causing both autoimmune diseases and a type of blood cancer called leukemia.
Autoimmune diseases happen when the immune system mistakenly attacks the body’s own healthy cells, thinking they’re dangerous. Leukemia, on the other hand, is a cancer that affects blood and bone marrow.
At first, these two health problems may seem very different. But researchers noticed something strange: many people with leukemia also have autoimmune diseases. This raised a big question—could the two be linked?
To explore this, scientists looked closely at a special type of immune cell called a “killer T cell.” These cells normally help by finding and destroying harmful cells, like those infected by viruses.
But the study found that when certain genes change, these killer T cells can go rogue. Instead of protecting the body, they start causing harm. They might attack healthy cells, which leads to autoimmune disease. Or, they might stop working properly and allow cancer to grow, like leukemia.
The researchers focused on a gene that controls a protein called STAT3. This protein helps guide how immune cells behave. In the study, scientists collected blood samples from children with rare autoimmune diseases.
Then, using a powerful tool called CRISPR (which allows scientists to edit genes), they changed the STAT3 protein in mice. The result was surprising: even if just a tiny number—only 1 to 2 percent—of T cells went rogue, it was enough to trigger serious autoimmune problems.
This small number having such a big effect was a major discovery. It means that even a few out-of-control immune cells can cause major damage. And if those same rogue cells also avoid killing cancer cells, they may help cancer like leukemia develop.
Understanding how this happens is a huge step forward. It could change the way doctors diagnose and treat these diseases. For example, in the future, doctors might use special tests to scan a person’s blood and find these dangerous cells before they cause harm. Scientists may also find ways to stop or remove these rogue cells using medicines that already exist.
Dr. Etienne Masle-Farquhar, who led the study, believes that these findings bring us closer to better treatments. If doctors can learn to recognize which cells are likely to go rogue, they can act earlier to stop disease. The study was published in the scientific journal Immunity.
In short, your immune system is usually your best line of defense. But when just a few of its cells stop following the rules, they can cause serious harm. This new research gives us hope that by understanding these rare events, we can one day prevent or better treat diseases like autoimmune disorders and leukemia.
If you care about cancer risk, please read studies that exercise may stop cancer in its tracks, and vitamin D can cut cancer death risk.
For more health information, please see recent studies that yogurt and high-fiber diet may cut lung cancer risk, and results showing that new cancer treatment may reawaken the immune system.
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