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 Total 5 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(1-2)], 2.0–3.0 years [SCIT(2-3)], and 3.0–3.5 years [SCIT(3-3.5)]) showed that the percentage of ILC2s was not significantly different between SCIT(1-2), SCIT(2-3), and SCIT(3-3.5) groups (SCIT(1-2) vs. SCIT(2-3): P = 0.268; SCIT(1-2) vs. SCIT(3-3.5): P = 0.635; and SCIT(2-3) vs. SCIT(3-3.5): 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.