Methods: Peripheral blood mononuclear cells were collected from peanut allergic (PA, n=16), peanut sensitised (PS, n=4) and non-atopic adult controls (NA, n=16). PA and PS underwent double-blind placebo-controlled food challenges (DBPCFC) to peanut, as part of the TRACE Peanut study. ILC2s, IL-5+, IL-13+ and IL-5+IL-13+ ILC2s were immunophenotyped as lineage negative CD127+CD294+ cells, using flow cytometry.
Results: The proportion of ILC2s in peripheral blood was higher in PA compared to NA (3fold, p=0.0006). IL-5+ ILC2s and IL-5+IL-13+ ILC2s were raised in PA compared to NA individuals (4fold, p=0.0026; 29fold, p=0.0002). ILC2s were increased following a positive food challenge in PA (1.2fold, p=0.0137), however, no changes were observed after a non-reactive challenge. IL-5+, IL-13+ and IL-5+IL-13+ ILC2s showed no significance difference in the non-active challenges, whereas in response to peanut there was a substantial change in the IL-13+ ILC2s (2fold, p=0.0029).
Conclusions: For the first time, we show that the frequency of ILC2s is higher in peanut allergic patients and may contribute to the pathophysiology of peanut allergy.