Women get autoimmune diseases much more often than men. Scientists at the Garvan Institute and UNSW Sydney have discovered why. Autoimmune disease happens when the body’s defense system attacks its own healthy parts. Lupus, for example, hits about nine women for every man.
More Than a Thousand Genetic Switches
In a huge study, researchers looked at the tiny switches that turn genes on or off inside immune cells. They found more than 1,000 switches that work differently in females and males. These switches make women’s immune cells fire up inflammation pathways more often, which may lead to more auto‑immune attacks.
Looking at Cells One by One
Old methods mixed all blood cells together, hiding the special traits of each cell type. New single‑cell tools let scientists study each cell individually. The team examined 1.25 million blood cells from about 1,000 healthy volunteers.
Male cells showed higher numbers of monocytes, the “first‑responders” that rush to danger. Their genes focused on basic cell upkeep and protein building. Female cells, on the other hand, had more B cells and regulatory T cells, and they lit up many genes linked to inflammation.
Why This Matters
A more alert immune system can protect us better, but staying on high alert also raises the chance that the system will mistake the body’s own tissue for an enemy. That mistake is what creates autoimmune disease.
Where the Switches Are Located
Scientists expected most of the sex‑specific switches to sit on the X or Y chromosomes. Surprisingly, most were found on the regular chromosomes that both sexes share, called autosomes.
Connecting the Dots to Lupus
Some of the discovered switches control two genes that are known to be involved in lupus. This helps explain why lupus appears far more often in women.
Looking Ahead to Better Treatments
Current medicines often suppress the whole immune system, which can cause side effects. Knowing the exact genetic pathways that differ between men and women could lead to therapies that target the problem without weakening the entire defense system.
In short, the study shows that male and female immune systems are built differently at the genetic level, offering a new reason why women are more vulnerable to autoimmune illnesses.