Absence of IgE neosensitization in house dust mite allergic patients following sublingual immunotherapy

Background The impact of sublingual immunotherapy (SLIT) on IgE neosensitization remains to be evaluated in large cohorts of patients. Objectives The aim of this study was to assess the dynamics of antibody responses induced in patients with allergic rhinitis during a 12-month treatment with sublingual tablets of house dust mites (HDM) allergen extracts. Methods Antibody responses were assessed in relationship with neosensitization and clinical benefit in sera from 509 European house dust mite-allergic patients before and after 1year of daily sublingual immunotherapy, using tablets containing Dermatophagoides pteronyssinus plus D farinae extracts or placebo (ClinicalTrials.gov NCT00674700). Patients were followed for one additional year after treatment cessation. IgE and IgG4 antibodies specific for mite extracts or purified group 1, 2 and 10 allergens were assessed using Immulite, Immunocap and ISAC assays. Results After 1year of SLIT, mite-specific IgE and IgG4 titres increased by 1.5-fold and fourfold, respectively, in the active, but not in the placebo group. A strong IgG4 induction occurred in a subgroup (i.e. 1015%) of immunoreactive patients, without any correlation with improvement in the average adjusted symptom score. Pre-existing IgE levels to purified mite allergens were not impacted during immunotherapy, and no de novo IgE responses to group 1, 2, 10 allergens were induced in patients who were unsensitized prior to immunotherapy. Similarly, no IgE neosensitization to wheat germ or yeast components used in the mite culture medium was observed. Conclusions and Clinical Relevance We document in a cohort of 509 patients followed over a 2-year period that SLIT does not induce any IgE neosensitization to allergens contained in the vaccine, such as groups 1, 2 as well as the food-related group 10 allergen. This observation further corroborates the safer safety profile of SLIT over SCIT.