There may be new hope for children with severe peanut allergy, a condition that not only is potentially fatal, but also can cause much anxiety for both children and parents alike.
This week, 2 new studies discuss research findings on the use of oral immunotherapy in children with peanut allergies, which affects up to 1.4% of children in high-income countries. Oral immunotherapy involves having individuals with an allergy to a substance ingest a tiny amount of that substance under close clinical monitoring, and gradually increasing this exposure over an extended period of time. The goal is to eventually reach a point where the body can tolerate a reasonable amount of the substance without a severe allergic reaction, at which point the individual is deemed “desensitized.”
The first study, released yesterday in The Lancet, is the first phase 2 randomized clinical trial showing that this type of immunotherapy may work for children with peanut allergies. Researchers at Cambridge University in England randomly assigned 99 children aged 7 to 16 years to receive either 6 months of oral immunotherapy or no treatment (aside from continuing to avoid exposure to peanuts). The oral immunotherapy involved feeding children daily peanut protein, starting with 2 mg and slowly increasing to 800 mg (roughly 5 peanuts) per day.
Of the 39 children who completed the oral immunotherapy regimen, 24 of them (62%) were successfully desensitized compared with none in the control group. Successful desensitization was defined as having no allergic reaction after ingesting 1400 mg of peanut protein (approximately 10 peanuts), as measured by a standard clinical test for food allergy called the double-blind, placebo-controlled food challenge.
As expected, children in the immunotherapy group had more adverse reactions than the control group, but most were mild and involved itching, mild wheezing, and rash. There were no serious adverse events.
Although these preliminary results are promising, much information is still lacking about how oral immunotherapy works on a molecular level. This is an area of active research, and a phase 1 study released today in the Journal of Allergy and Clinical Immunology may shed some light on this process.
The study, conducted by researchers at Stanford University, included 43 patients who were randomly assigned to either oral immunotherapy (a 24-month regimen culminating in exposure to 4000 mg of peanut protein) or no therapy. Of the 23 patients given oral immunotherapy, 20 became desensitized (or tolerant) to peanuts. The researchers then looked to see if tolerance to peanuts was maintained after the desensitized individuals stopped immunotherapy for 3 months and completely avoided peanut exposure. They found that among the 20 individuals who originally became desensitized, only 7 remained so after 3 months.
The Stanford team also looked at several immune system markers in the study participants. They found that the 7 participants who remained tolerant to peanuts had increased activity of a special type of T lymphocyte called the antigen-induced regulatory T-cell. Furthermore, specific genes in those T-cells had lower levels of DNA methylation, a process in which chemical tags are added to specific DNA segments (genes) that affect how those genes are expressed by the cell. These epigenetic changes in T-cell DNA (changes not in the DNA code itself, but in the patterns of chemical tags attached to it) might be one of the underlying mechanisms for peanut desensitization following oral immunotherapy, although more research is needed on the topic.
Ultimately, oral immunotherapy is still very much an experimental therapy that is far from routine clinical use. “Further studies in wider populations are needed,” noted Pamela Ewan, MD, one of the authors on the Lancet study, in a statement. “It is important to note that oral immunotherapy is not a treatment people should try on their own and should only be done by medical professionals in specialist settings,” she cautioned.