Allergic Reactions Exacerbated by Estrogen

A study investigating allergic reactions in mice has indicated that estrogen plays a role in triggering anaphylaxis, providing a potential clue as to why women experience severe allergic reactions more frequently than men.

The study, published online on December 29, 2014, in the Journal of Allergy and Clinical Immunology, found that a type of estrogen known as estradiol enhanced the levels and activity of endothelial nitric oxide synthase (eNOS), an enzyme responsible for several anaphylactic symptoms.

While female mice typically experience more severe and longer lasting anaphylactic reactions than male mice, this gender disparity disappeared after the research team inhibited eNOS activity. The research team also found that the severity of the allergic responses of female mice was reduced to a level comparable to that of males after the females were given estrogenblocking treatments.

“Our study defines a contribution of estrogen through its regulation of eNOS expression and nitric oxide production to vascular hyperpermeability and intensified anaphylactic responses in female mice, providing additional mechanistic insights into risk factors and possible implications for clinical management in the further exploration of human anaphylaxis,” concluded the study authors.

The National Institute of Allergy and Infectious Diseases, which sponsored the study, noted in a press release that further research is needed to determine whether estrogen has a similar effect in humans.