The immune systems of men and women respond very differently to infection — and scientists are taking notice. Research presented last week at a microbiology meeting in Boston, Massachusetts, suggests that the split could influence the design of vaccination programmes and lead to more targeted treatment of illness.
Now, scientists are beginning to tease out some precise mechanisms. At the meeting, infectious-disease researcher Katie Flanagan at the University of Tasmania in Australia reported on a tuberculosis vaccine given to Gambian infants. She found that the vaccine suppressed production of an anti-inflammatory protein in girls, but not boys. This boosted the girls’ immune responses, and may have made the vaccine more effective.
Hormones also play a part. Oestrogen can activate the cells involved in antiviral responses, and testosterone suppresses inflammation. Treating nasal cells with oestrogen-like compounds before exposing them to the influenza virus has revealed further clues, says Sabra Klein, an endocrinologist at Johns Hopkins University in Baltimore, Maryland. Only the cells from females responded to the hormones and fought off the virus (J. Peretz et al. Am. J. Physiol. http://doi.org/bj5w; 2016).One of the more intriguing studies mentioned is one that compares immune responses before and after sex-change operations.
A study set to begin later this year could help to tease apart the relative influence of genes and hormones on infection. Altfeld and his colleagues will look at 40 adults going through sex-change operations. If female hormones are responsible, the transgender women in the study should begin mounting stronger immune reactions to infections and develop more autoimmune problems than the transgender men.These kinds of results, when combined with advances in regenerative medicine, are among the reasons why we can expect to see continued increases in life expectancy among humans.