A new study has warned that women are at a greater risk for deadly allergic reactions because of their primary female sex hormones, oestrogens. This could explain why men are not as likely to be admitted into hospitals having severe problems of this nature. It was found that oestradiol, a type of oestrogen, enhances the amount of chemical activity that drives allergic reactions that are life threatening, in a study by the National Institute of Allergy and Infectious Diseases (NIAID), in the United States.
When an individual experiences anaphylaxis, which is an allergic reaction from medication, food, or insect bites and stings, immune cells release enzymes; tissues swell and blood vessels widen as a result. In more extreme cases of allergic reactions, swelling can be so significant that it will lead to problems with breathing, heart attack or shock. In earlier clinical studies, results showed that women usually experience anaphylaxis more frequently than men, but the cause of this difference is not understood.
In the UK, around 21 million adults have at least one allergy and approximately 10 million suffer from multiple allergies. Hospital admissions have increased greatly — about 5 times as many since 1990…the most common problems being those from seafood, insect stings, nuts and milk. In the UK, around 20-30 deaths caused by anaphylaxis occur every year. In the US, current estimates show about 1,500 deaths each year.
Female mice were found to experience longer lasting and more severe anaphylactic reactions than males in the study, which was published in The Journal of Allergy and Clinical Immunology. Oestrogen influences blood vessels and enhances activity and levels of endothelial nitric oxide synthase, eNOS– an enzyme that causes certain anaphylaxis symptoms.
Gender differences disappeared when researchers blocked the activity of eNOS. The extent of their allergic reaction was reduced and responses shown as similar to those seen in males when given oestrogen blocking treatments. But, more study is needed to see if these effects are similar in humans and could possibly be used toward drugs to prevent women from suffering possible deadly attacks in the future.