Men and women’s immune systems age in fundamentally different ways
Women tend to mount stronger immune responses than men — but their immune systems also appear to shift more dramatically as they age.
Researchers analysed thousands of individual immune cells from people across a range of age groups, examining both the types of cells present and the activity of genes within those cells. The picture that emerges is not straightforward. In women, age-related changes in immune cell populations are markedly larger than in men — but that doesn’t necessarily mean women fare worse. It means the system responds more strongly to the passage of time, and in some cases in qualitatively different ways.
One of the most striking findings concerns genes involved in autoimmune activity — situations where the immune system attacks the body’s own tissues. These genes showed greater age-related changes in expression in women, which could help explain why autoimmune diseases like rheumatoid arthritis and lupus are more common in women and often increase after menopause. Oestrogen likely plays a regulatory role, and its decline leaves measurable traces in immune biology.
When the body’s defences start to wear out
The gradual deterioration of the immune system with age has a name: immunosenescence. It shows up as increased vulnerability to infections, a weaker response to vaccines, and a higher risk of cancer. But here too, men and women appear to follow different paths. Some cell types decline with age; others shift in their relative proportions. The study shows that the pattern of which cells change, and how, differs substantially between the sexes.
The practical implications are real. Vaccination schedules, dosages of immune-modulating drugs, and risk profiles for infectious diseases have largely been built on data that pools men and women together. If the underlying immune biology differs fundamentally, standard recommendations may be suboptimal — or even misleading — for certain groups.
A field that has long ignored sex differences
The findings connect to the broader concept of inflammaging — the low-grade chronic inflammation that accumulates with age and is linked to virtually all major age-related diseases, from dementia to cardiovascular disease. Whether inflammaging unfolds differently in women than in men, and whether that partly explains differences in disease patterns across a lifetime, is a question this research raises without fully answering. For decades, biomedical research treated the male body as the default. Studies like this one are beginning to dismantle that assumption — slowly, but with growing force.