Study On Immunostimulatory Activity Of CpG ODN Against Immunity-low Mice And Human Cord Blood Lymphocytes

Objective: To investigate immunostimulatory activity of CpG ODN against immunosuppression mice, aged mice, pregnant mice and their newly born mice; To screen a CpG ODN that its immunostimulatory activity against human cord blood lymphocytes is stronger than others; To observe immunostimulatory activity of CpG ODN against premature infants cord blood lymphocytes and to observe its cytolysis against Kse2 cells. Methods: All mice were received an injection into the left tibialis anterior muscle with HBsAg vaccine or both HBsAg vaccine and CpG 1826 that was generally accepted as the optimal CpG ODN in mice, then mice were boosted at 2 weeks with the same formulation as was used at prime. The specific antibody IgG and IL-12 were measured by ELISA. Spleen lymphocytes evaluation was undertaken using hematoxylin and eosin-stained paraffin sections in light microscope. We designed six phosphorothioate CpG ODNs according to the law of CpG ODN design , one CpG ODN that its immunostimulatory activity against human cord blood lymphocytes is stronger than others was screened by MTT. Immunostimulatory activity of CpG ODN against premature infants cord blood lymphocytes was observed by MTT and its cytolysis against K562 cells was observed by LDH. Results: There was an significant increase in anti-HBsAg IgG and IL-12 when CpG ODN was mixed with HBsAg vaccine in immunity suppression model mice; there were also significant increases in anti-HBsAg IgG and IL-12 when 10 g and 20 g CpG ODN were mixed with HBsAg vaccine in aged mice. But 20 g CpG ODN cann't enhance the immunity of pregnant mice and their newly born mice. We screened out CpG ODN4 that has highly immunostimulatory activity against term infants and premature infants cord blood lymphocytes. We also showed that the immunostimulatory activity of CpG ODN4against term infants cord blood lymphocytes was stronger than those of premature infants. We observed CpG ODN4 had strong cytolytic activity against K562 cells. Conclusions: CpG ODN can improve the immunity of immunosuppression mice, aged mice, but 20 g CpG ODN cann't enhance the immunity of pregnant mice and its newly born mice. Human specific CpG ODN has highly immunostimulatory activity against human cord blood lymphocytes.