HLA-DR⁺ regulatory T cells and IL-10 are associated with success or failure of desensitization outcomes

Background: Omalizumab (XOLAIR®)-assisted multi-food oral immunotherapy (mOIT) has been shown to safely, effectively, and rapidly desensitize patients with multiple food allergies. In our clinical trial (NCT02626611) on omalizumab-assisted mOIT, different desensitization outcomes (success or failure of desensitization) were observed following a period of either continued or discontinued mOIT. However, the association between the immunological changes induced by omalizumab-assisted mOIT and desensitization outcomes has not yet been fully elucidated. In this study, due to the key roles of regulatory T (Treg) cells and the type 2 helper T cell (Th2) pathway in immune tolerance to food allergens, we aimed to characterize their association with the desensitization outcomes of omalizumab-assisted mOIT. Methods: Mass cytometry and multiplex cytokine assays were performed on blood samples obtained from participants with allergies to peanut, cashew, or milk in our phase 2 clinical study (NCT02626611). Comprehensive statistical and bioinformatic analyses were conducted on high-dimensional cytometry-based single-cell data and high-throughput multiplex cytokine data. Results: Our results demonstrated that the frequency of HLA-DR⁺ Treg cells, and the production of Th2 cytokines (IL-4, IL-5, IL-13, and IL-9) as well as the immunoregulatory cytokine IL-10 by peripheral blood mononuclear cells (PBMCs) was significantly increased in cultures with allergen compared to cultures with media alone at baseline (Week 0). We also observed increased frequency of allergen responsive HLA-DR⁺ Treg cells and enhanced production of IL-10 by PBMCs in participants who achieved successful desensitization compared to those with failure of desensitization. However, the production of Th2 cytokines by PBMCs did not show significant differences between participants with different desensitization outcomes (success vs. failure of desensitization), despite omalizumab-assisted mOIT inducing a significant reduction in the production of Th2 cytokines. Conclusions: We demonstrated that the frequency of HLA-DR⁺ Treg cells and IL-10 cytokine production by PBMCs are associated with desensitization outcomes of omalizumab-assisted mOIT. These findings suggest potential immunological parameters that could be targeted to enhance desensitization success rates.