[Protective efficacy induced by dendritic cells pulsed with GST in combination with CpG oligodeoxynucleotide against Schistosoma japonicum infection].

ABSTRACT

OBJECTIVE: To study the protective effects on the infection of Schistosoma japonicum in C57BL/6 mice induced by dendritic cells DCs pulsed with GST in combination with CpG oligodeoxynucleotide. METHODS: GST was purified and used to stimulate DC2.4 cell line. Antigen loading was analyzed by immunofluorescence method. Thirty-five C57BL/6 mice were divided into seven groups(5 mice per group). Mice in groups A, B, C, D and E were immunized subcutaneously with DCs, DCs treated with PSA, DCs pulsed with GST, DCs stimulated with GST+CpG ODN, DCs stimulated with CpG ODN, respectively. For the above five groups, each mouse received 100 microl cell suspension at the density of 10(7)/ml subcutaneously for three times at 2-week intervals. Each mouse of group F was immunized subcutaneously with 50 microg GST formulated in complete Freund's adjuvant first, and 50 microg, 10 microg GST respectively in incomplete Freund's adjuvant for the last two doses. Group G received PBS and served as control. Serum samples were collected 10 days after the final immunization, and were analyzed for specific antibodies by ELISA. At two weeks after the final immunization, each mouse were challenged by 30 +/- 1 cercariae of S. japonicum. Six weeks after infection the mice were sacrificed, and number of worms was counted. RESULTS: Light green fluorescence was observed in dendritic cells under the fluoroscope after pulsing with GST which indicated the protein loaded dendritic cells. The IgG level in groups C, D and F was 0.555 2 +/- 0.078 9, 0.715 0 +/- 0.052 3, and 2.127 0 +/- 0.411 5, respectively, all higher than that of group G (P < 0.05). The worm reduction rate of group D was 53.3%, followed by group F (24.0%) and group C (21.3%). There was no significantly difference in the worm reduction rate between group D and groups F and C (P > 0.05). CONCLUSION: Dendritic cells pulsed with GST in combination with CpG oligodeoxynucleotide induce significant immunoprotection against the infection of Schistosoma japonicum.