Written by Joshua Feblowitz
One hundred years ago, a British scientist by the name of Leonard Noon attempted to treat hay fever by injecting patients with of small amounts of grass pollen. Inspired by successful vaccines for diseases like smallpox, Noon hoped to cure patients of their allergy by helping them build up an “active immunity” to the pollen.
In his laboratory at St. Mary’s Hospital in London, Noon carefully prepared “pollen extracts” to test his theory. To study patients’ reactions to pollen, he sprinkled the extract directly into their eyes – undoubtedly a very unpleasant experience, as anyone with seasonal allergies can imagine. Finally, he injected patients with the extract over several weeks in increasing amounts, successfully reducing their sensitivity to the pollen.
Noon’s 1911 study represents the first successful example of allergen immunotherapy, a treatment that involves gradually exposing an allergic person to an allergen to coax their immune system into tolerating the substance. Although Noon never uses the word “allergy” in his original paper – at the time the term was just 4 years old—his discovery marked the beginning of a new era for allergy research and treatment. Today, allergen immunotherapy continues to be employed by innovative researchers around the world, including right here at Children’s Hospital Boston.
In many ways, modern techniques are similar to those used by Noon one hundred years ago: patients are deliberately exposed to the small amounts of the allergen over an extended period and, over time, develop a tolerance to the allergen. (Thankfully, Noon’s practice of forcing dust in patients’ eyes is a thing of the past.) As these therapies became more sophisticated over time, they have yielded successful treatments for allergies to pollen, insect stings and pet dander. Immunotherapy now comes in several forms, including allergy shots (subcutaneous immunotherapy), drops placed under the tongue (sublingual immunotherapy) and even ingesting the allergen itself (oral immunotherapy).
“Immunotherapy has changed a great deal over the last century,” says Dale Umetsu, MD, PhD, a professor of pediatrics in the Division of Immunology. “Therapy is more standardized and more effective and we are able to successfully treat many patients with environmental allergies.”
Food allergies, however, have been a different story. “Food allergy immunotherapy was tried many decades ago,” says Umetsu, “But, unfortunately, when given by injection, it tends to cause a fair amount of reactions.”
Recently, however, armed with greater scientific knowledge of food allergies and modern medications, Umetsu and his colleagues have begun to tackle allergens far more severe than grass pollen, such as milk and peanuts. Last year, his research team at Children’s Hospital’s Allergy and Asthma Program completed a successful oral immunotherapy study, curing 11-year-old Brett Nasuti, and several other children, of severe milk allergies.
To desensitize these children to milk, Umetsu’s team used a carefully calibrated regimen that involved gradually increasing doses of milk given over numerous visits and the administration of the drug omalizumab (Xolair), which blunts the symptoms of an allergic reaction by blocking the antibodies that react to the food and trigger symptoms. Using the medication Xolair in addition to the immunotherapy allowed researchers to avoid potentially severe reactions and shorten the amount of time needed to develop a tolerance to the allergen.
“The idea of immunotherapy for food allergies has been around for a long time,” says Umetsu. “But now there’s a lot of excitement, especially around the use of Xolair, which may potentially make desensitization available to many more patients in the future.”
Following the successful milk study, Dr. Umetsu is hoping for similar results combating peanut allergies. As part of a new trial, children with severe peanut allergies will receive a similar immunotherapy involving Xolair and small doses of peanuts. With any luck, they hope to help these children fully overcome their severe peanut allergies.
“Most recent studies are focused more on making it safe for the patient to tolerate accidental exposure,” says Umetsu. “In our studies, we want patients to actually be able to partake in a meal that includes the allergen.”
This innovative research provides hope that a cure for food allergies could eventually be developed. In recent years, the number of children with food allergies has been growing increasing rapidly with no signs of abating. Today, roughly 3 million children in the United States have some form of food allergy. “We need to find a better way to deal with this problem, says Umetsu. “Telling patients just to avoid the food is just not very satisfying.”
By combining the essential tool developed one hundred years ago by Leonard Noon with modern knowledge and medication, Umetsu and his colleagues hope to make significant strides against the rising tide of pediatric food allergies. “We are trying to work on a cure and get it into the clinic,” he says. “That’s our end goal.”
For additional information on the current peanut desensitization trial, contact our experts at the Allergy and Asthma Program.