Can you provide data showing testosterone lowering the immune system? Thanks.
Scientists have found that men with relatively high amounts of circulating testosterone benefit less from vaccination against influenza than do men with lower testosterone levels.
med.stanford.edu
Additional analyses showed that testosterone reduces levels of certain transcription factors (regulatory proteins) that ordinarily prevent Module 52 genes from “turning on.” In other words, higher testosterone levels result in more Module 52 expression. Several Module 52 genes have known immune-system connections; activation of one of these genes, for example, results in the accelerated differentiation of cells whose job it is to suppress, rather than foster, immune response. These connections make the interactions of the genes with testosterone an intriguing target of further exploration by immunologists, physiologists and drug researchers, Davis said.
But perhaps more intriguing, to many, is this: Why would evolution have designed a hormone that on the one hand enhances classic male secondary sexual characteristics, such as muscle strength, beard growth and risk-taking propensity, and on the other hand wussifies men’s immune systems?
The evolutionary selection pressure for male characteristics ranging from peacocks’ plumage to deer’s antlers to fighter pilots’ heroism is pretty obvious: Females, especially at mating-cycle peaks, prefer males with prodigious testosterone-driven traits.
Davis speculates that high testosterone may provide another, less obvious evolutionary advantage. “Ask yourself which sex is more likely to clash violently with, and do grievous bodily harm to, others of their own sex,” he said. Men are prone to suffer wounds from their competitive encounters, not to mention from their traditional roles in hunting, defending kin and hauling things around, increasing their infection risk.
While it’s good to have a decent immune response to pathogens, an overreaction to them — as occurs in highly virulent influenza strains, SARS, dengue and many other diseases — can be more damaging than the pathogen itself. Women, with their robust immune responses, are twice as susceptible as men to death from the systemic inflammatory overdrive called sepsis. So perhaps, Davis suggests, having a somewhat weakened (but not too weak) immune system can prove more lifesaving than life-threatening for a dominant male in the prime of life.