To investigate the effect of sublingual immunotherapy (SLIT) on the expression of type 2 innate lymphocytes (ILC2) and the level of cytokine IL-13 in peripheral blood of children with mite-induced allergic asthma, in order to further clarify the mechanism of SLIT in asthma.

Forty children with mild to moderate mite-induced allergic asthma were chosen from the Department of Respiratory Medicine in Northern Jiangsu People′s Hospital from February 2016 to January 2017. All children were sensitized to Dermatophagoides Farianae and/or Dermatophagoides Pteronyssinus and have received anti-asthma drug therapy for 3 months. The children were equally divided into two groups to receive either SLIT combined with anti-asthma drug (SLIT group) or anti-asthma drug alone (drug group). Total asthma symptoms score (TASS) and total medications score (TMS) of the two groups were compared at baseline, the end of 6 months of treatment and the end of one year of treatment. The expression of ILC2 and the level of cytokine IL-13 secreted by ILC2 in peripheral blood of the two groups were also compared at the above three time points. For data with homogeneity of variance (age, TASS, TMS, the expression of ILC2 and the level of cytokine IL-13), one-way analysis of variance was used for comparisons. The t-test was used to compare the differences in TASS, TMS and peripheral blood ILC2 between groups and different time points, as well as the differences in peripheral blood IL-13 between groups and between those at baseline and the end of 6 months of treatment. The rank sum test was used to compare peripheral blood IL-13 at the end of one year treatment between groups.

The TASS in the SLIT group were (1.95±0.69), (1.10±0.60) and (0.70±0.66) at baseline, the end of 6 months of treatment and the end of one year of treatment, respectively; posttreatment TASS were significantly lower than that at baseline (P=0.01; P=0.001). The TASS of the drug group were (2.25±0.76), (1.75±0.52) and (1.10±0.64) at baseline, half a year after treatment and one year after treatment, respectively; posttreatment TASS were significantly lower than that at baseline (P=0.03; P<0.001). After treatment, the TASS in the SLIT group were significantly lower than those in the drug group (t=1.79, P=0.08; t=2.32, P=0.03). In the SLIT group, TMS were (2.10±0.72), (1.50±0.51) and (0.70±0.57) at baseline, half a year of treatment and one year after treatment, respectively; posttreatment TMS were significantly lower than that at baseline (P=0.003; P<0.001). TMS of the drug group at baseline, treatment for half a year and one year after treatment were (2.20±0.83), (1.55±0.61) and (1.20±0.62) score, respectively; posttreatment TMS were significantly lower than that at baseline (P=0.004; P=0.12). After one year of treatment, TMS in the SLIT group was significantly lower than that in the drug group (t=2.66, P=0.01). The expression of ILC2 in the SLIT group was (2.96±0.30)%, (2.47±0.20)% and (2.05±0.19)% at baseline, half a year after treatment and one year later, respectively; posttreatment expression of ILC2 was significantly lower than that at baseline (P<0.001). The expression of ILC2 in the drug group was (2.94±0.26)%, (2.87±0.27)% and (2.28±0.21)% at baseline, half a year after treatment and one year later, respectively; ILC2 expression at one year of treatment was significantly lower than that at baseline (P<0.001). After treatment, the expression of ILC2 in the SLIT group was significantly lower than that in the drug group (t=5.36, P<0.001; t=3.73, P<0.001). IL-13 levels in the SLIT group were (21.67±1.13)%, (20.34±1.03)% and (18.17±1.33) % at baseline, half a year after treatment and one year later, respectively; posttreatment IL-13 levels were significantly lower than that at baseline (P<0.001). The levels of IL-13 in the drug group were (21.99±0.83)%, (21.83±0.81)% and (19.08±0.63)% at baseline, half a year after treatment and one year later, respectively; IL-13 level at one year of treatment was significantly lower than that at baseline (P<0.001). After treatment, IL-13 levels in the SLIT group were significantly lower than those in the drug group (t=5.05, P<0.01; Z=2.76, P=0.01).

Drug therapy combined with SLIT can significantly reduce drug use. SLIT can significantly reduce the percentage of ILC2 in peripheral blood of children with asthma, and down-regulate the level of cytokine IL-13.