A previous report showed that CD69+ peripheral blood eosinophils in patients with allergic asthma were not reduced after treatment with omalizumab [24], consistent with our in vitro experiment, in which omalizumab did not inhibit CD69 expression on eosinophils; however, we confirmed that serum-soluble CD69 in the patients with ECRS and severe asthma was reduced in the responders to omalizumab treatment, which indicates that soluble CD69 could reflect the activity of eosinophilic inflammation in severe cases. Here, CD69 is linked to allergic asthma.