Project-002

PROJECT SUMMARY Food allergy is increasingly prevalent in the United States, and approximately one-third of patients have reactivity to multiple foods. There is an unmet clinical need to treat multi-food allergy in a timely and efficacious manner, but the mechanistic factors that should guide selection of an optimal treatment strategy are unclear. This project aims to obtain fundamental new understanding of human B cell and immunoglobulin (Ig) responses in patients allergic to multiple foods, and to analyze the B cell alterations induced by multi-allergen oral immunotherapy (multi-OIT) alone or in combination with biologics targeting IgE or the IL-4/IL-13 receptor component IL-4Rα. We will use flow cytometry isolation of allergen-specific B cells, focusing on cells specific for milk, peanut or cashew allergens, paired with DNA deep sequencing of immunoglobulin (Ig) gene rearrangements, to characterize pathogenic B cell populations in allergic patients, and to determine what changes in clonal populations, antibody isotype expression, antibody somatic mutation, and affinity are induced in these B cell populations during successful multi-OIT treatment. We will evaluate whether there are B cell repertoire features, either prior to multi-OIT, or during multi-OIT, that predict participants’ responses and could be used to guide therapy. The studies will be performed on specimens from well-characterized multi-allergic participants in the pilot, phase 2 multi-OIT clinical trial proposed in Project 1, as well as from appropriate atopic and healthy control subjects. We will evaluate and compare the molecular features of B cells and antibodies specific for milk, peanut and cashew allergens, and their alterations in response to multi-OIT, within the same people. In a subset of participants, we will study B cells in both blood and GI biopsy specimens, to determine to what extent peripheral blood B cell monitoring accurately reflects the allergic disease state in the GI tract of patients, and the changes induced by multi-OIT. Importantly, we will also analyze the effects of monoclonal antibody therapies targeting IgE or IL-4Rα during multi-OIT, to determine the extent to which these biologic therapies affect the nature and time course of B cell changes induced by multi-OIT. We will additionally perform long-term follow up studies of B cells in participants in our POISED and MAPX OIT trials. The B cell data from this Project will be combined and analyzed together with clinical data and experimental data from T cells and basophils from Projects 1, 3 and 4, and Core B, in collaboration with the Data Analysis Core C, to enable a comprehensive evaluation of immunological phenotypes associated with multi-food allergic disease, and with successful and durable therapeutic responses to multi-OIT.