P087 Activation-induced cell death of natural killer cells by IL-15 in asthma and atopy patients

Introduction IL-15 has been known to promote differentiation, proliferation and activity of NK cells, but its role has not been investigated for activation-induced cell death (AICD) of NK cells from asthma and atopy patients. Methods NK cell population was analyzed by flow cytometry. IL-15 gene expression was investigated by quantitiative RT-PCR. NK cytotoxicity was determined by LDH assay. Results NK cell population was diminished in peripheral blood mononuclear cells (PBMC) of asthma and atopy patient groups compared with healthy donor group. IL-15 gene expression and NK cytotoxicity were enhanced in NK cells purified from PBMC of both patient groups. In addition, intracellular reactive oxygen species (ROS) levels were also elevated in NK cells of both patient groups. Interestingly, incidence of apoptosis was increased in NK cells of both patient groups. Furthermore, treatment of recombinant human IL-15 induced production of intracellular ROS and expression of apoptosis-associated genes in NK cells of both patient groups. Conclusion These results suggest that the reduced NK cell population may be due to AICD by IL-15-induced ROS in asthma and atopy patients.