Is the immune system in men and women different?
Adam Moeser, the Matilda R. Wilson Endowed Chair, Associate Professor of Large Animal Clinical Sciences, Michigan State University has written a comprehensive review of potential differences between the efficacy of the immune system between males and females. Clinicians and researchers have suspected since a long time that there are differences in how men and women respond to infectious challenges but the research community has largely ignored these apparent differences. Adam Moeser explains why we should be looking into this in the future.
Could sex differences in immune system play a role?
In general, females have a more robust immune response than men which may help females fight off infections better than males. This could be a result of genetic factors or sex hormones such as estrogen and testosterone.
Biological females have two copies of the X chromosome, which contains more immune genes. While the genes on one X chromosome are mostly inactive, some immune genes can escape this inactivation, leading to double the number of immune-related genes and thus double the quantity of certain immune proteins compared with biological men who have only one X chromosome.
Sex hormones such as estrogen and testosterone can also impact the immune response. In one study, researchers showed that activating the estrogen receptor in female mice provided them protection against SARS-CoV. And there is an approved clinical trial that will examine the effects of estrogen patches on the severity of COVID-19 symptoms.
It is, however, interesting that the current data showing that women have better survival rates than men apply to even men and women in the 80-plus age group when hormone levels in both sexes equalize. This suggests that factors other than adult sex hormone levels are contributing to sex differences in COVID-19 mortality.