Genes regulated by testosterone may impact flu vaccine response

Human genes regulated by testosterone may impact antibody responses to influenza vaccines, according to a study recently published in Proceedings of the National Academy of Sciences. The study, led by Stanford University researchers, may partially explain why men typically have weaker responses to vaccines than women. Previous research showed that men usually experience more severe viral and microbial infections than women, who tend to have stronger immune responses to vaccinations and infections. In the new study, the research team analyzed the antibody responses of 53 women and 34 men to the 2008-2009 seasonal influenza vaccines. Women produced antibodies that in laboratory tests were more able to effectively neutralize the flu virus than the men. The researchers looked for patterns in gene expression to explain the difference. Gene expression is the degree to which certain genes are turned on or off. The men with weak responses to vaccines tended to have high expression levels of a particular cluster of genes involved in the metabolism of fats. Prior studies suggested that testosterone might be responsible for regulating the expression of many of these genes. The scientists determined that men with high levels of testosterone and elevated expression of the gene cluster mounted weaker antibody responses to the vaccine than women and men with low testosterone. The research suggests that testosterone may suppress immune responses to vaccines by changing expression patterns of certain genes. The researchers, who were supported in part by the National Institute of Allergy and Infectious Diseases, said further research is needed to determine how testosterone changes expression patterns of the gene cluster.