When a peanut-butter sandwich can kill you, you learn to be careful. But two new studies could begin to ease worries about peanut allergies. One suggests that avoiding skin lotions containing peanut oil for babies and toddlers might lower their risk of developing peanut allergies. In the other, researchers report the first drug that effectively blocks the dangerous allergic reaction in people.
To investigate how children develop allergies, allergist Gideon Lack of St. Mary's Hospital in London and his colleagues examined data from a long-term study of 13,971 English preschool children. They identified children with a history of peanut allergy and asked their mothers what foods they ate during pregnancy and breastfeeding and what sorts of lotions they rubbed on their babies. Moms' peanut-eating habits made no difference. But 19 of 21 allergic children had been exposed to peanut-oil-containing lotions and creams, nearly twice the percentage as nonallergic kids, the team reports in the 6 March issue of the New England Journal of Medicine.
Those who already have food allergies now have few alternatives other than avoidance. A new drug could change that, according to a report in the same journal. A team including immunologist Donald Leung of National Jewish Medical and Research Center in Denver and Hugh Sampson of Mount Sinai School of Medicine in New York City and colleagues reports that a drug called TNX-901 effectively blocks an allergic reaction to peanuts before it can get started.
Peanut allergies are triggered when antibodies belonging to a class called IgE bind to peanut proteins in the blood. IgEs then cluster on the surface of immune cells, which releases molecules such as histamine that trigger hives, difficulty breathing, and sometimes even loss of consciousness and death. Treating patients with TNX-901--itself an antibody that mops up IgE--desensitized the patients. Treated patients could tolerate the equivalent of about nine peanuts, 18 times more than untreated patients and enough to protect them from most accidental exposures, the authors say. Unfortunately, clinical trials on TNX-901 are stalled while three companies that worked together to develop the drug--Tanox, Genentech, and Novartis--battle in court.
The British study is "particularly important" because "there aren't a lot of clues" how food allergies develop, says immunologist Henry Metzger of the National Institute of Arthritis and Musculoskeletal and Skin Diseases in Bethesda, Maryland. And the TNX-901 study is "a beautiful example of what we're all trying to do: take our basic understanding of these cellular systems from the lab bench to the bedside," he says.
Background on food allergies from the Food Allergy & Anaphylaxis Network
Frequently asked questions on food allergies from the Food Allergy Research and Resource Program at the University of Nebraska, Lincoln