Objective:To investigate the regulatory role of TLR7/8 ligand R-848 on IgE production of murine purified B cells. Methods:CD19+B cells were purified with MACS from splenocytes of murine, and cultured with base medium, and medium with anti-CD40 plus IL-4 in the presence or absence of R-848. The concentration of IgE was determined with ELISA,and the activation of B cells was determined with FACS. Purified B cells were labeled with CFSE, and after culturing the cells were harvested and the division of cells was determined with FACS. Results:R-848 could inhibit IgE production of purified B cells stimulated with anti-CD40 plus IL-4 in a dose dependent manner, and enhance the activation of B cells. Moreover, R-848 could inhibit the division of B cells stimulated with anti-CD40 plus IL-4. Conclusion:The inhibitory role of R-848 on IgE production might be related with a reduction in B cell division.