ABSTRACT
AIM: To investigate enhancement of immune response to hepatitis B vaccine in immunosuppressed mice by CpG oligodeoxynucleotide (ODN). METHODS: Immunodepressed C57BL/6 mice caused by cytoxan were given an injection of either hepatitis B vaccine alone or hepatitis B vaccine and CpG ODN into the left tibialis anterior muscle, then the mice were given another shot after 2 weeks using the same formulation. Blood was collected at 5 weeks after immunization and anti-hepatitis B surface antigen IgG and IL-12 levels were measured by ELISA. Spleens of immunized mice were observed under microscope. RESULTS: There was a two-fold increase in anti-hepatitis B surface antigen IgG level when hepatitis B vaccine was mixed with CpG ODN to immunize immunodepressed mice. There was a significant increase in IL-12 level when hepatitis B vaccine was mixed with CpG ODN. Under optical microscope, there were fewer lymphocytes in immunodepressed mice than in normal control group. The proliferation level of spleen lymphocytes in CpG ODN group was elevated compared with that of normal control group and nuclei of lymphocytes became larger. CONCLUSION: CpG ODN can enhance the immune response to hepatitis B vaccine in immunodepressed mice.
