Effect of interleukin-33 on Th1/Th2 cytokine ratio in peripheral lymphocytes in asthmatic mice

Background Allergic asthma is a chronic airway inflammatory disease partly characterised by high concentration of T help 2 （Th2） cytokines in bronchoalveolar lavage fluid （BALF）. There is no report on the relation of peripherally circulating blood lymphocytes and asthma. We explored the balance of Th2fThl cytokines in asthmatic mice. Exogenous recombinant interleukin （IL） 33 acted on murine peripheral circulating blood lymphocytes, IL-5 cytokine was selected for assessing Th2 cytokines and interferon-gamma （IFN-~） for Thl cytokines. Methods Female specific pathogen free BABL/c mice were sensitised by intraperitoneal injection of 20 IJg of ovalbumin emulsified in 1 mg of aluminium hydroxide gel in a total volume of 200 IJI, and challenged for 30 minutes in 7 consecutive days with an aerosol of 2 g ovalbumin in 100 ml of PBS. Then we collected BALF and isolated lymphocytes from the peripheral blood. The lymphocytes were divided into two groups： asthmatic group and normal group. Thl/Th2 cytokines was detected by enzyme-linked immunosorbent assay （ELISA） kits. Results In the asthma group, we found numerous eosinophils and lymphocytes on the glass slides. We then confirmed that the optimal concentration of IL-33 was 10 ng/ml and time of IL-33 stimulating lymphocytes was 24 hours. In the asthma group, the production of IL-5 was significantly increased over normal group after stimulation with IL-33 （P 〈0.05） and the production of IFNy was supressed from IL-33 stimulated lymphocytes （P 〈0.05）. Conclusion IL-33 acts on lymphocytes of peripheral blood increasing secretion of Th2 cytokines and inhibiting secretion of Thl cytokines.