Abstract: 　Objective To invesigate the immunoregulatory effect of immunostimulatory DNA sequence (ISS ) on the production of Th1 and Th2 cytokines induced by mite allergen in PBMC of the patients with mite allergic asthma in vitro . Methods PBMC from the patients with allergic asthma and normal controls were isolated and cultured in vitro stimulated by ISS and Dermatophagoides farinae allergen (Df). IL 12, IFN γ and IL 5 in the cell supernatants were detected by ELISA. Df specific IgE in sera of patients were assayed by fluorescent enzyme immunoassay. Results PBMC from both the patients and normal controls stimulated by ISS plus Df produced a significant increase in the level of both IFN γ and IL 12 compared with non ISS and Df stimulations, whereas IL 5 was decreased. Moreover, the levels of IFN γ, IL 12 produced were significantly higher in normal controls than in the patients, on the contrary, IL 5 was down regulated. It was also shown that the level of IL 12 produced by PBMC of the patients with ISS plus Df stimulation correlated positively with that of IFN γ. Conclusion ISS not only promotes the expressions of Th1 cytokines but also downregulates the production of Th2 cytokines induced by Df in both allergic and non allergic individuals, indicating its potential application in the immunotherapy of mite allergy.

Key words: immunostimulatory DNA sequence, Dermatophagoides farinae, asthma, cytokine