Estrogen found to aggravate severe allergic reactions

Washington: Scientists have claimed that Estradiol, a type of estrogen, worsens allergic reactions.

Researchers from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), found that the estrogen boosts the levels and activity in mice of an enzyme that drives life-threatening allergic reactions.

The study results may help explain why women frequently experience more severe allergic reactions compared to men. Furthermore, the results reaffirm the importance of accounting for gender in the design of animal experiments.

Anaphylaxis is an allergic reaction triggered by food, medication or insect stings and bites. Immune cells, particularly mast cells, release enzymes that cause tissues to swell and blood vessels to widen. As a result, skin may flush or develop a rash, and in extreme cases, breathing difficulties, shock or heart attack may occur. Clinical studies have shown that women tend to experience anaphylaxis more frequently than men, but why this difference exists is unclear.

In the current study, researchers found that female mice experienced more severe and longer lasting anaphylactic reactions than males. When the researchers blocked eNOS activity, an enzyme that causes some of the symptoms of anaphylaxis, the gender disparity disappeared. In addition, giving estrogen-blocking treatments to female mice reduced the severity of their allergic responses to a level similar to those seen in males.