Statistically, women live longer than men. In France, in 2020, life expectancy at birth was 85.1 years for women compared to 79.1 years for men, a difference of six years. In addition to these longevity benefits, women are also more resistant to most health threats and benefit more from vaccines. This phenomenon is largely caused by a more efficient immune system compared to men. These disparities are found all over the world, throughout the ages, but how can we explain them?
Recent research in the fields of immunology, virology and genetics, presented by New Scientist, is starting to reveal the causes of this biological advantage. Hormones and XX sex chromosomes play an important role in the activation of immune cells, which detect, fight and remember pathogens better than in men.
Scientific studies show that much of this immune advantage lies in the female sex chromosomes. As explained Duygu Ucar, immunologist at the Jackson Laboratory in Connecticut (United States), the X chromosome carries many genes related to immunity and having two copies of this chromosome provides additional protection.
Therefore, women benefit from greater genetic diversity, their receptors react more quickly and effectively against various pathogens: their bodies detect infections earlier and thus gain an advantage. This could also explain why women are 20 percent less likely to get cancer, because cancer cells often lose the function of genes that normally suppress tumors.
The key role of estrogen
Some of these genes are located on the X chromosome: if one of them has an abnormality, a second copy can correct the error. In contrast, certain male genetic profiles, including certain lineages of the Y chromosome in men of European descent, increase the risk of coronary heart disease due to excessive inflammation and reduced immune response. Additionally, a gene called UTY appears to make some men more susceptible to complex immune-related diseases.
Female hormones also play an important role. Estrogen, in particular, strengthens innate immunity (the body’s first line of defense) and adaptive immunity (memory acquired over time), activating cells such as neutrophils, which are important for eliminating infectious agents. Sarthak Gupta’s research (National Institutes of Health, United States) highlights that estrogen potentiates these killer cells and optimizes the immune response.
In addition, estrogen stimulates the production of B lymphocytes, the basic cells of the humoral response that produce antibodies and consolidate immune memory. In many species, females retain these memories longer than males – a major evolutionary advantage. This may also explain the better vaccine response in women.
However, biomedical research still pays little attention to things specific to women. Historically, research models have been largely based on male biology, as pointed out by Caroline Duncombe (Stanford University, California). “Biological sex remains one of the main factors influencing health and disease throughout life, as it impacts genetics, hormones, lifestyle and the environment”he explained. This bias represents a challenge for both women and men: investigating women’s immune mechanisms could open new therapeutic pathways for both sexes.
