Natural killer cells in allergic rhinitis patients and nonatopic controls

Allergic rhinitis (AR) is currently considered to be a worldwide problem. The role of type 2 cytokines in this disease has been established, and natural killer (NK) cells are possibly the source of cytokine secretions. This study was performed to confirm the existence of type 2 cytokine-secreting NK cells in AR patients and to determine their characteristics.

Twenty AR patients and 20 healthy nonatopic controls were included. Peripheral blood mononuclear cells were separated from heparinized blood by density gradient centrifugation. NK cells were enriched and cultured for 72 h. Cytokine secretion was measured by ELISA, and cytotoxicity assay was carried out using the PKH2-labeled K562 cell line. Intracytoplasmic cytokine staining and an analysis of surface markers of NK cells were performed on freshly isolated peripheral blood mononuclear cells using flow cytometry.

Patients with AR had a higher percentage of NK cells compared to nonatopic subjects. The mean percentage of IL-4+ NK cells was significantly higher and that of IFN-γ+ NK cells was nonsignificantly lower in AR patients compared to healthy nonatopic controls. IL-13 secretion was also significantly higher in AR patients compared to nonatopic controls. While there was no difference between the case and the control groups with regard to the surface expression of CD40, CD45RO, and CD95, the expression of CD178 was significantly higher in the cases when compared to the controls. NK cell cytotoxicity was also significantly higher in AR patients compared to healthy controls.

This study confirms the existence of type 2 cytokine-secreting NK cells in AR and shows their increased number and enhanced cytotoxicity compared to normal individuals.