Suppression of Immunotherapy on Group 2 Innate Lymphoid Cells in Allergic Rhinitis

Background:Group 2 innate lymphoid cells（ILC2s）are regarded as a novel population of lineage-negative cells that induce innate Type 2 responses by producing the critical Th2-type cytokines interleukin（IL）-5 and IL-13.ILC2s as key players in the development of allergic rhinitis（AR）have been proved,however,the effect of subcutaneous immunotherapy（SCIT）with dermatophagoides pteronyssinus extract（Der p-SCIT）on ILC2s in AR patients is not clear.This study aimed to investigate the response of ILC2s of peripheral blood in house dust mites（HDM）-sensitized Chinese patients with AR who received SCIT with Der P extract.Methods:Seven healthy controls without symptoms of AR who had negative reactions to any of the allergens from skin-prick testing,nine patients diagnosed with persistent AR according to the Allergic Rhinitis and its Impact on Asthma（ARIA）guidelines,and 24 AR patients who received Der p-SCIT for 1.0-3.5 years were recruited for the study.ILC2s in the peripheral blood were evaluated using flow cytometry.The severity of their symptoms of all participants was rated based on the Total 5 symptom score.Results:Among 40 participants,9 AR patients were assigned to the untreated group,24 AR patients receiving Der p-SCIT were assigned to the immunotherapy group,and 7 healthy controls without symptoms of AR were assigned to healthy control group.The mean Total5 symptom score of immunotherapy group was significantly lower than that of untreated group（4.3±1.4 vs.10.1±2.5,P<0.001）.Similarly,the levels of ILC2s in the peripheral blood of immunotherapy group were significantly reduced compared with that in untreated group（P<0.001）,but were not significantly different from healthy controls（P=0.775）.Further subgroup analysis based on the duration of SCIT therapy(1.0-2.0 years[SCIT;],2.0-3.0 years[SCIT;],and 3.0-3.5 years[SCIT;])showed that the percentage of ILC2s was not significantly different between SCIT;,SCIT;,and SCIT;groups(SCIT;vs.SCIT;:P=0.268;SCIT;vs.SCIT;:P=0.635;and SCIT;vs.SCIT;:P=0.787).Conclusions:The present study highlighted the suppression of Der p-SCIT on ILC2s in HDM-AR patients.ILC2s identified in peripheral blood can be used as an effective biomarker for Der p-SCIT.