A new blood test has been devised that can predict which people will have severe allergic reactions to peanuts, seafood, and other foods.

Mount Sinai researchers, writing in The Annals of Allergy, Asthma & Immunology, said the new method marks an improvement on existing skin-prick and blood tests that measure levels of allergen-specific IgE (sIgE) — a protein made by the immune system — when exposed to certain foods and substances.

Such so-called “challenge tests” can flag allergies but cannot predict the severity of allergic reactions, which for some people can be life threatening.

In a new study, Mount Sinai researchers from the Mindich Child Health and Development Institute and the Jaffe Food Allergy Institute said the new method — called the basophil activation test or BAT — detects the numbers of one type of immune cell activated by exposure to a food to accurately predict the severity of each person's allergic reaction.

It requires only a small blood sample and provides quick results.

"While providing crucial information about their potential for a severe allergic reaction to a food, having blood drawn for BAT testing is a much more comfortable procedure than food challenges," says researcher Ying Song, M.D.

"Although food challenges are widely practiced, they carry the risk of severe allergic reactions, and we believe BAT testing will provide accurate information in a safer manner."

To test the new method, researchers took blood samples from 67 patients, who also underwent a food challenge with a placebo or with peanut, tree nut, fish, shellfish, or sesame. The results showed the BAT test results correlated with food challenge results, but also provided deeper insight into the severity of the participants’ allergies.