House Dust Mite Major Allergens Contributes Significantly to Specific IgG4 Response during Allergen Immunotherapy DOI: https://doi.org/10.1016/j.jaci.2015.12.1244 Abstract: Rationale Allergen-specific IgG4 increases during allergen specific immunotherapy (AIT). In this study, specific IgG4 against the individual major allergens of dust mites during AIT was investigated. Methods Patients of allergic rhinitis (n=52) sensitized to dust mite were treated with subcutaneous immunotherapy using standardized D. pteronyssinus (Dp) extract. Patients with allergic rhinitis (n=14) sensitized to dust mites who received medications alone were controls. Specific IgE and IgG4 against Dp, D.farina(Df) and corresponding major allergens of group 1 (Dp1 and Df1) and group 2 (Dp2 and Df2) were measured before AIT, 6 months and 12 months later. Results Combined symptom and medication scores significantly decreased in immunotherapy group. Specific IgG4 against Dp1, Df1, Dp2 and Df2 allergens increased significantly during AIT (Dp: 0.3, 0.99, 2.72; Dp1: 0.16, 0.67, 2.04; Dp2: 0.10, 0.49, 1.49; Df: 0.38, 1.04, 2.62; Df1: 0.12, 0.37, 1.01; Df2: 0.1, 0.44, 1.27. before AIT, 6 months and 12months later respectively, mgA/L). Of the correlations between dust mite extract IgG4 and the individual subgroup allergen IgG4, it was shown that there were strong correlations in terms of both concentrations (after 12 months: Dp-Dp1: r=0.99; Dp-Dp2: r=0.93; Df-Df1: r=0.93; Df-Df2: r=0.95) and levels of increase (after 12 months: Dp-Dp1: r=0.69; Dp-Dp2: r=0.59; Df-Df1: r=0.90; Df-Df2: r=0.77) (P<0.0001 for all). With the same testing instrument (UniCAP system), Df1 and Df2 IgG4 contributed 87% to Df specific IgG4 response, whereas Dp1 and Dp2 contributed 130% to Dp IgG4 response at the 12 months of AIT. Conclusions Our findings underscores the importance of major allergens in AIT standardization and design. All Authors: Jianjun Chen Yiwen You Yue Zhou Yanjun Wang Weijia Kong