Abstract: OBJECTIVE To explore the possible therapy mechanisms of ganoderma lucidum polysaccharides on asthma inflammation, the expression of glucocorticoid-induced tumor necrosis factor receptor (GITR) and its ligand (GITRL)at asthmatic rat alveolar macrophages were observed. METHODS Forty Clean-level SD rats were randomly divided into four groups including asthma group, control group, dexamethasone intervention group (DXM group) and ganoderma lucidum polysaccharides intervention group, alveolar macrophages were separated and purificated from the bronchoalveolar lavage fluid(BALF). And the expressions of GITR/GITRL mRNA and protein at alveolar macrophages were detected respectively by Real-time quantitative reverse transcription polymerase chain reaction(QRT-PCR) and immunocytochemistry. RESULTS The expressions of GITR/GITRL mRNA and protein in asthma group were significantly higher than those in the control group (P<0.05 or P<0.01). Moreover, the expressions of them in ganoderma lucidum polysaccharides intervention group and in DXM group were significantly lower than those in asthma group(P<0.05 or P<0.01). Dramatically, the expressions of GITR/GITRL protein in ganoderma lucidum polysaccharides intervention group were significantly higher than those in DXM group(all P<0.05). But there was no statistically significant difference of GITR/GITRL mRNA between two groups. Furthermore, in ganoderma lucidum polysaccharides intervention group, the total number of cells calculation in BALF was significantly lower than that in asthma group(P<0.01). And the pathological inflammation change in lung tissue were strongly lessened either. And there were significantly positive correlated between GITR and GITRL about mRNA or protein(all P<0.01). CONCLUSION Ganoderma lucidum polysaccharides can down regulated the GITR/GITRL signal system at alveolar macrophages, and reduces the total number of cells calculation in BALF, and lessened the pathological inflammation in lung tissue. Result shows there are some therapy roles of ganoderma lucidum polysaccharides on ansthma. But this function is weaker than dexamethasone.