Increased innate type 2 immune response in house dust mite-allergic patients with allergic rhinitis.

Group 2 innate lymphoid cells (ILC2s) are essential in initiating and driving allergic immune responses. However, there were inconsistent findings of the ILC2 levels in allergic rhinitis (AR) patients. This study investigated the ILC2 levels in the peripheral blood of house dust mite (HDM)-sensitized AR patients and their ability to secrete type 2 cytokines. The levels of ILC2s with phenotypic ILC2 characteristics were increased in the HDM-AR patients. The AR patients' symptom score and IL-13 levels were positively associated with the ILC2s in HDM-AR patients. The epithelial cytokine stimulation induced dramatic production of IL-5 and IL-13 in PBMCs of AR patients. We successfully sorted ILC2s from AR patients and identified their ability of type 2 cytokines production. The number of ILC2s increased in the HDM-AR patients and ILC2s produced the amount of TH2 cytokines in the presence of epithelial cytokines, which suggested the important role of ILC2 in AR patients.