IDO1 and allergic asthma: Consistent with the results from the studies mentioned above, the present clinical study revealed higher IDO levels and larger Treg populations in healthy children than in pediatric patients with allergic asthma, with a significant positive correlation between IDO level and Tregs; in contrast, IDO level exhibited a negative correlation with the Th17/Treg ratio, as patients with allergic asthma had markedly reduced IL-6 levels and significantly elevated IL-10 levels.