Group 2 Innate Lymphoid Cells: New Players in Peanut Allergy
Saturday, March 5, 2016
South Exhibit Hall H (Convention Center)
Elisavet Ntavli, Paul J. Turner, FRACP PhD, Robert J. Boyle, MBChB PhD, Andrew Clark, MRCPCH MD, Abigail O Robb, B.Sc, Stephen R. Durham, MA MD FRCP, Mohamed H. Shamji, BSc MSc PhD FAAAAI
Rationale: Group 2 innate lymphoid cells (ILC2s) are morphologically similar to lymphocytes, lack lineage markers, express the prostaglandin D2 receptor (CD294 or CRTH2), IL-7Rα, CD127 and secrete predominantly IL-5 and IL-13. They have been associated to asthma or allergic rhinitis, however, their role is yet to be defined in peanut allergy. We hypothesized that ILC2s are involved in the pathophysiology of peanut allergy and that their frequency is increased following peanut allergen challenge.

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.