Credit: Sherry Yates Young/Science Photo Library
An experimental vaccine protects genetically modified mice against severe allergic reactions for up to a year, according to research1 published today in Science Translational Medicine. Scientists say the findings show that vaccination is a promising approach for preventing allergic reactions.
The vaccine targets an antibody called immunoglobulin E (IgE), which is bound to immune cells in the body’s tissues and circulates in small amounts in the blood. Immune cells also produce IgE in response to proteins found on potential threats, including viruses, toxic substances and parasites such as worms and blood flukes (Schistosoma haematobium). The antibody tells the body to release histamine, which triggers symptoms such as coughing, wheezing and hives. It can also trigger a potentially fatal reaction called anaphylaxis, a widespread reaction across the body that can cause swelling of the tongue or throat, shock and difficulty breathing. In people with allergies, IgE is produced in response to proteins that do not usually cause harm, such as those found in peanuts, cat dander and other allergens.
The vaccine triggers the production of antibodies that bind to IgE and stop it from binding to immune-cell receptors. That leaves less IgE available for generating an immune response after exposure to an allergen.
The findings are an “exciting proof of concept” that a vaccine can trigger the production of antibodies against IgE, says Mimi Tang, an allergy and immunology researcher at the Murdoch Children’s Research Institute in Melbourne, Australia.
The vaccine works in a similar way to the injectable therapy omalizumab, the first monoclonal antibody approved to treat food allergies. But it could offer longer-lasting protection than omalizumab, which requires injections every two weeks to maintain its effect, says Tang. The vaccine is a promising scientific concept, but it’s still at a very early stage, she adds.
DIY antibodies
When the research team tested the vaccine in mice genetically modified to be prone to severe allergic reactions, eight of nine unvaccinated control mice died within 30 minutes of exposure to an allergen. Vaccinated mice, by contrast, showed only mild signs of an allergic reaction, and none died. They also maintained high levels of antibodies against IgE up to 52 weeks after immunization.
Attempts to create an anti-allergy vaccine in the 1990s were unsuccessful, says co-author Laurent Reber, who studies allergic diseases at the Toulouse Institute for Infectious and Inflammatory Diseases (Infinity) in France. But Reber and his colleagues were able to test their vaccine in mice modified to express the human IgE receptor, a technology that was not available 30 years ago.
