OBJECTIVE To investigate whether murine recombinant interferon-gamma (IFN-gamma) is capable of inhibiting antigen-induced eosinophil (EOS) infiltration into the mouse airway. METHODS BALB/c mice were sensitized and challenged repeatedly with ovalbumin (OVA) to develop an allergic airway inflammation model. The experimental mice were given injection of different doses of IFN-gamma. The numbers of EOS in bronchoalveolar lavage fluid (BALF) from each group were counted, and concentrations of interleukin (IL)-5 in supernatants of cultured spleen cells were detected. RESULTS In sensitized mice challenged with OVA 20 minutes once a day for 6 days, the number of BLAF EOS was 9.53 +/- 0.84 x 10(5)/ml. However, no EOS could be found in BALF from mice without OVA sensitization and challenge. In mice treated with IFN-gamma, doses of IFN-gamma (1.0 x 10(3), 1.0 x 10(4), 1.0 x 10(5)U/KG) produced 29.8% (P < 0.05), 55.7% (P < 0.01), and 69.0% (P < 0.01) inhibition of eosinophilia, respectively. The results also showed that IFN-gamma prevented antigen-induced EOS recruitment into airway accompanied be decrement of levels of IL-5 with a dose-related response. CONCLUSIONS IFN-gamma is capable of inhibiting EOS infiltration into mouse airway by inhibiting the production of IL-5. Our results suggested that IFN-gamma may be of value in treating asthma in human beings.