Cytokine dynamics in FPIES during acute phase and stable status
To verify whether the elevation in serum IL-2 and IL-10 was specific to the symptomatic period, we compared the levels of the two cytokines in symptomatic and asymptomatic stages in samples from FPIES patients (Figure 2 ). The results showed that the serum levels of both cytokines were significantly higher in the symptomatic than in the asymptomatic period (IL-2 median values: 218.7 pg/mL vs. <2.6 pg/mL, p = 0.002; IL-10 median values: 31.8 pg/mL vs. 5.2 pg/mL, p < 0.001). Thus, serum IL-2 and IL-10 returned to normal levels when the symptoms disappeared.
Alterations in serum levels of IL-2 and IL-10 during OFC
Next, we evaluated the alterations of serum IL-2 and IL-10 levels during the OFC test in patients No. 6 and No. 7 (Figures 3A and 3B ). The patients were challenged with causative foods and showed vomiting 3 and 2 hours later, respectively. Notably, a marked increase in the serum levels of IL-2 and IL-10 were observed immediately after vomiting. In patient No. 5, both IL-2 and IL-10 levels were higher at the time of vomiting than 6 hours after the beginning of the OFC (Figure 3C ). In contrast, no elevation was observed in the two cytokine levels before the OFC test and 24 hours after the beginning of the OFC test. In contrast, this increase was not clearly observed in the FPIES-resolved subject.