Research published today in Science Translational Medicine has shown that immune cells with a distinct protein profile are found in the blood of patients with diverse environmental and food allergies (including peanut, pollen, pet dander and mold) but absent from individuals who do not have allergic conditions.
This new finding, from a team of researchers led by Erik Wambre, PhD, of Benaroya Research Institute in Seattle, holds promise for advances in both diagnosis and treatment. The study was supported by the National Institutes of Health, with FARE contributing supplemental support to the Wambre Laboratory.
As a detectable biomarker, the allergy-specific cells could be monitored to assess the effectiveness of immunotherapy. As a target for drug development, the cells could aid in the discovery of new therapies for a broad range of allergic conditions.
“This could make research much more directed, since scientists can now focus on the specific cells involved in generating allergies,” said James R. Baker, Jr., MD, CEO and chief medical officer of FARE.
The allergy-specific cells described in the study belong to the Th2 class of immune cells, which help defend against extracellular parasites such as roundworms. Immunologically active proteins called cytokines that are secreted by these Th2 (type 2 helper T) cells promote responses involving IgE antibodies and eosinophils. An allergic reaction results when these immune responses are directed against otherwise harmless proteins. Both allergic and non-allergic individuals have Th2 cells. However, the researchers identified several ways in which the proteins made by a subset of Th2 cells found in allergy patients but not in non-allergic controls differ from the proteins of typical Th2 cells. When activated, these allergy-specific Th2 cells (Th2A) produce a wider variety of cytokines in larger amounts. These results point to a possible role for Th2A cells in allergic disease.
One source of samples for this research was blood drawn from participants in a clinical trial of peanut oral immunotherapy using CODIT, a characterized peanut flour produced by Aimmune Therapeutics. These patients provided blood samples before and after an initial double-blind placebo-controlled food challenge and after the patient had been treated with either CODIT or a placebo. The initial food challenge was found to stimulate activity in Th2A cells but not conventional Th2 cells, indicating that the Th2A cells participate in the allergic response. At the end of treatment, 78 percent of subjects who received CODIT passed a 1,043 mg peanut protein food challenge, a dose that none of the participants who received placebo could tolerate. As CODIT-treated patients became desensitized to peanut, their Th2A cells became significantly less abundant, while the levels of allergy-specific Th2A cells in the placebo-treated patients did not decrease.
“This is the first time we’ve had a way to accurately measure the allergy process and assess whether therapies are working,” Wambre said in a press release from Benaroya Research Institute.
Wambre’s continuing work in this area is being funded by FARE. In 2015, Wambre received a five-year $750,000 FARE Investigator in Food Allergy Award to support his work on T cell responses to peanut allergic components.