Why Females Have More Severe Allergic Reactions Than Males: Estrogen

When it comes to allergic reactions, estrogen is the worst thing for them. Scientists have found that estradiol, a type of estrogen, enhances the levels and activity in mice of an enzyme that drives life-threatening allergic reactions.

Anaphylaxis is an allergic reaction that's 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 breathing difficulties can occur.

That's why studying this allergic reaction is so important. In the latest study, scientists found that female mice experience more severe and longer lasting anaphylactic reactions than males. Instead of targeting immune cells, estrogen influences blood vessels and enhances the activity of endothelial nitric oxide synthase (eNOS), an enzyme that causes some of the symptoms of anaphylaxis. When the researchers blocked eNOS activity, though, the gender disparity disappeared.

The findings reveal a bit more about anaphylaxis. More important, it shows the role that estrogen can play. In fact, giving estrogen-blocking treatments to female mice reduced the severity of their allergic responses to a level similar to those seen in males.

The recent study reveals the role of estrogen and may pave the way for treatments to prevent severe allergic reactions in humans. That said, more work is needed to see if the effects are indeed similar in people.

The findings are published in the Journal of Allergy and Clinical Immunology.

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