Peanut oral immunotherapy (OIT), which involves daily micro-dosing with peanut protein, has been shown to desensitize some people with peanut allergy. Research is still needed to determine the optimal treatment regime in terms of OIT dose and duration that will confer permanent protection.
The Lancet has recently published a study that followed people who had participated in an OIT trial. It showed that while OIT was successful in many people, those who discontinued or continued the therapy at a reduced dose had less protection against allergy symptoms when later exposed to peanut protein. Interestingly, tests results from blood samples taken before the participants started OIT gave an indication of whether or not the therapy would be successful for each individual.
The study was carried out at Stanford University, and involved 120 people aged 7 to 55 with diagnosed peanut allergy. Some were given OIT dosing with peanut protein for 2 years, while others received a placebo. All participants avoided all other sources of peanut until a medically-controlled peanut challenge was undertaken. Of those participants who received peanut OIT, 83 per cent did not react to the peanut challenge, while only 4 per cent on the placebo passed.
Among those who passed the first challenge, some were given a reduced dose of peanut protein for a further 12 months, while others received a placebo. A further food challenge was then undertaken. Only 37 per cent of those on the micro-dose passing this test, and even fewer (13 per cent) of those in the placebo group passed.
Blood tests showed that participants who passed the food challenges had lower initial levels of allergic antibodies to peanut protein and other indicators of allergic activity in the blood.
More studies are required to determine how useful OIT might be as a long-term protection strategy against peanut allergy.
Reference: Chinthrajah et al. 2019. The Lancet DOI: 10.1016/S0140-6736(19)31816-1