Scientists Discover Why Women Are More Predisposed to Autoimmune Diseases

Newly discovered sex-specific differences in the immune system help explain why women are more predisposed to autoimmune diseases compared to men, scientists report, as cited by Reuters.

Over 1,000 genetic “switches” function differently in the immune cells of women and men, leading to higher activity of inflammatory processes in women, according to a study published in The American Journal of Human Genetics.

In autoimmune diseases – such as lupus, multiple sclerosis, and rheumatoid arthritis – the immune system mistakenly attacks the body’s own healthy cells, leading to chronic inflammation, tissue damage, and problems with joints, skin, and organs.

Researchers analyzed over 1.25 million immune cells from the blood of nearly 1,000 healthy volunteers in Australia.

Using technology that allows for single-cell analysis, scientists discovered sex-specific genetic variations that previous studies failed to detect because they measured the average activity of large groups of cells.

Particular attention was paid to so-called expression quantitative trait loci – genetic mechanisms that act as regulators of how strongly a given gene is activated or suppressed.

In women, genetic activity was strongly directed toward inflammatory pathways, with higher levels of B-cells and regulatory T-cells recorded.

In men, genetic activity was more associated with basic cellular functions and protein synthesis, as well as higher levels of monocytes – cells that act as the first line of immune defense.

“This highly reactive immune profile gives women an advantage in fighting viral infections, but it comes at a biological cost – a higher predisposition to autoimmune diseases,” said Dr. Sarah Ballouz from the University of New South Wales.

She added that immune cells in men are less prepared for inflammatory responses, making men more susceptible to infections.

“Our results show that the immune system must be studied while taking sex differences into account,” said the study’s lead author, Dr. Seyhan Yazar from the Garvan Institute of Medical Research.

“Although we know that the immune systems of men and women differ, many studies still overlook these differences, which limits our understanding of diseases and can lead to bias in treatment,” she added.