Motivation: The availability of databases identifying allergenic proteins via a transparent and consensus-based scientific approach is of prime importance to support the safety review of genetically-modified foods and feeds, and public safety in general. Over recent years, screening for potential new allergens sequences has become more complex due to the exponential increase of genomic sequence information. To address these challenges, an international collaborative scientific group coordinated by the Health and Environmental Sciences Institute (HESI), was tasked to develop a contemporary, adaptable, high-throughput process to build the COMprehensive Protein Allergen REsource (COMPARE) database, a publicly accessible allergen sequence data resource along with bioinformatics analytical tools following guidelines of FAO/WHO and CODEX Alimentarius Commission.Results: The COMPARE process is novel in that it involves the identification of candidate sequences via automated keyword-based sorting algorithm and manual curation of the annotated sequence entries retrieved from public protein sequence databases on a yearly basis; its process is meant for continuous improvement, with updates being transparently documented with each version; as a complementary approach, a yearly key-word based search of literature databases is added to identify new allergen sequences that were not (yet) submitted to protein databases; in addition, comments from the independent peer-review panel are posted on the website to increase transparency of decision making; finally, sequence comparison capabilities associated with the COMPARE database was developed to evaluate the potential allergenicity of proteins, based on internationally recognized guidelines, FAO/WHO and CODEX Alimentarius Commission

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RATIONALE: Group 2 innate lymphoid cells (ILC2s) are morphologically similar to lymphocytes, lack lineage markers, express the prostaglandin D2 receptor (CD294 or CRTH2), IL-7Ra, 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, n516), peanut sensitised (PS, n54) and non-atopic adult controls (NA, n516). PA and PS underwent double-blind placebocontrolled 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, p50.0006). IL-5 + ILC2s and IL-5 + IL-13 + ILC2s were raised in PA compared to NA individuals (4fold, p50.0026; 29fold, p50.0002). ILC2s were increased following a positive food challenge in PA (1.2fold, p50.0137), 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, p50.0029). 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.

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Peanut allergy is associated with the presence of CD154+ Th2A and Tfh13 cells. The use of a single activation marker such as CD154 at a single time-point after stimulation, may bias the detection of terminal effector cells. Our objective was to track the dynamics of T cell in response to peanut to obtain a more comprehensive picture of allergen-specific immunity associated with disease. PBMCs from peanut allergic (n=65), food allergic but peanut tolerant (n=5), and healthy controls (n=3) were incubated with a peanut extract for 6–48 h. Cell activation was monitored by conventional and high dimensional flow cytometry (30-marker panel) and cytokine production by cytokine capture assay. Analysis was performed by 2-D gating and unsupervised clustering (FlowSOM). Peanut induced an upregulation of CD154/CD69 on mature effector memory cells that was observed at 6h and maintained for 48h. Cytokine capture showed secretion of IL-2, -4, -13, and -5 from these cells, which peaked at 6 h. The use of additional timepoints and activation markers identified two additional subsets specifically associated with disease: CD137+ and OX40/CD25 on other two cell subsets after 24 h. CD137+ cells secreted IFN-g, while OX40/CD25 cells secreted none of the cytokines tested. OX40/CD25 cells were reduced by IL-2 neutralization and likely include bystander activated cells. Clustering by FlowSOM analysis confirmed the identity of these three unique clusters, and provided additional phenotypic markers for CD154+ (CCR4+/CCR6+), CD137+ (CXCR3+), and CD25/OX40 (Foxp3+CD27−). Analysis of the dynamics of peanut-induced T cell activation revealed novel subsets including Th1 and regulatory cells co-existing with previously described highly differentiated Th2 cells.