Objective To investigate the inhibitory effect of IFN-γ on acute allergic airway inflammation induced by IL-33 in mice.Methods Twenty-four female C57BL/6 mice (6-8 weeks) were randomly divided into four groups: IL-33 model group, IFN-γ treatment group, IL-33+IFN-γ treatment group and PBS control group.A mouse model of acute allergic airway inflammation was induced by IL-33.Samples of bronchial alveolar lavage fluid (BALF) and lung tissues were collected.Group 2 innate lymphoid cells (ILC2s) and eosinophils were analyzed by flow cytometry.Levels of IL-5 and IL-13 in the supernatants of lung homogenate and BALF were measured by ELISA.Expression of IL-5, IL-13 and ST2 at mRNA level was detected by real-time PCR.Pathological changes in lung tissues were observed following hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) staining.Results Compared with the PBS control group, no infiltration with inflammatory cells, goblet cell hyperplasia or mucus secretion was observed in the IFN-γ group;the numbers of ILC2s and eosinophils were not affected by IFN-γ;the levels of IL-5 and IL-13 in the supernatants of BALF and lung homogenate, and the expression of IL-5, IL-13 and ST2 at mRNA level in lung tissues were not significantly changed by IFN-γ (P>0.05).Compared with the PBS control group, massive infiltration with inflammatory cells, excessive mucus secretion, increased numbers of ILC2s and eosinophils, up-regulated levels of IL-5 and IL-13 in the supernatants of BALF and lung homogenate, and enhanced expression of IL-5, IL-13 and ST2 at mRNA level in lung tissues were detected in the IL-33 model group (P<0.05).Compared with the IL-33 model group, the combined treatment with IL-33 and IFN-γ significantly alleviated inflammatory cell infiltration, inhibited mucus secretion, reduced the numbers of ILC2s and eosinophils, down-regulated the levels of IL-5 and IL-13 in the supernatants of BALF and lung homogenate, and suppressed the expression of IL-5, IL-13 and ST2 at mRNA in lung tissues (P<0.05).Conclusion IFN-γ can inhibit the proliferation of eosinophils and ILC2s induced by IL-33, and reduce the secretion of IL-5 and IL-13, which indicates that IFN-γ has an inhibitory effect on acute allergic airway inflammation induced by IL-33 in mice.