Objective: To investigate the activation level of NLRP3 inflammasome in immune thrombocytopenia ( ITP) and the effect of inhibiting NLRP3 mediated inflammasome activation on polarization and immune function of M1 macrophages. Methods : The expression of NLRP3 mRNA in peripheral blood mononuclear cells (PBMC) and CD14 + monocytes of ITP patients (ITP group) and Control group (Control group) was detected by RT⁃qPCR. The levels of IL⁃1β and IL⁃18 in serum of the two groups were determined by ELISA. M0 macrophages (MDMs) from ITP group were divided into 4 groups : IgG control group ( IgG group) , MCC950 treatment group ( MCC950 group) , LPS , IFN⁃γ and IgG treatment group (LPS + IFN⁃γ + IgG group) and LPS , IFN⁃γ and MCC950 treatment group (LPS + IFN⁃γ + MCC950 group) ; mRNA and protein levels of M1 macrophage markers CD86 , iNOS and MCP⁃ 1 were detected by RT⁃qPCR and Western blot. Western blot was used to detect the expression of NLRP3 inflammasome associated protein , ASC , Cleaved caspase⁃1 and IL⁃ β . Flow cytometry was used to detect the phagocytosis of MDMs on platelets in each group , and CFSE was used to detect the proliferation of CD4 + T and CD8 + T. Results: Compared with the control group , the expression of NLRP3 mRNA in PBMC and CD14 + monocytes , and the concentration of IL⁃1β and IL⁃18 in serum of ITP group increased significantly ( P < 0. 05 ) . Platelet counts were negative correlated with NLRP3 mRNA expression in CD14 + monocyte and the concentration of IL⁃1β , IL⁃18 in serum in patients with ITP ( P < 0. 05) . Compared with IgG group , the mRNA and protein expressions of M1 macrophage markers CD86 , iNOS , MCP⁃1 , and the protein expression level of NLRP3 , ASC , cleaved caspase⁃1 and IL⁃ β , the platelet phagocytosis and the proliferation promoting ability of CD4 + T and CD8 + T cells significantly increased in LPS + IFN⁃γ + IgG group and LPS + IFN⁃γ + MCC950 group ( all P < 0. 05) . Compared with LPS + IFN⁃γ + IgG group , the above indexes significantly decreased in LPS + IFN⁃γ + MCC950 group (P < 0. 05) . Conclusion The activation level of NLRP3 inflammasome in ITP is abnormally elevated , which was related to the excessive M1 polarization of MDMs. Inhibiting NLRP3 mediated inflammasome activation could attenuate the M1 polarization and immune function of macrophages.