Immunity Naturally Stronger in Women than Men

Kathleen Blanchard's picture

Researchers now say that women have stronger immune systems than men do. It seems that estrogen is responsible for the stronger natural immunity in women, compared to men. The result is better protection from bacterial infections.

Scientists from the Research Institute of the McGill University Health Centre and McGill University found that estrogen blocks production of an enzyme called Caspase-12. The result is a stronger immune defense for women. Caspase-12 activates harmful cytokines that can cause harm when released in large amounts in response to viruses and bacteria. Dr. Maya Saleh, lead researcher for the study says, "These results demonstrate that women have a more powerful inflammatory response than men.”


The researchers used infection resistant mice for the study, who lacking the Capsase-12 gene. When they implanted Capsase-12 in both male and female mice, only the males became vulnerable to infection. Dr. Saleh explains, "We were very surprised by these results, and we determined that the estrogen produced by the female mice blocked the expression of the human Caspase-12 gene.” The scientists were able to pinpoint the exact location where the estrogen receptor binds to the Capsase-12 gene, showing that the females possessed stronger naturally immunity that the males because of estrogen.

The findings are applicable to people, because human Capsase-12 genes were used to show the natural strong immunity found from the ability of estrogen to block inflammation. The researchers say immunity might be strong in women in men to protect the role of women in reproducing.

Synthetic hormones had the same effect as natural estrogen for keeping immunity strong. The findings that women have stronger immune systems than men, because of estrogen, could lead to an entirely novel way to help both men and women fight disease by boosting immunity using synthetic hormones.

McGill University Health Centre