[Molecular adjuvant C3d up-regulates both B7-1 and B7-2 expression on Raji cells].

To explore modulation of the molecular adjuvant C3d in the hCGbeta -C3d3 fusion protein in costimulatory molecule expression on Raji cells by linking to the surface molecule CD21. Raji cells, B cell line, were incubated with the purified hCGbeta-C3d3, hCGbeta or C3d3 protein for 15 hours respectively in the interference of anti-CD21 monoclonal antibody or not. The culture concentration of each group was 10, 30, or 90 microg/ml respectively. The expression of both B7-1 and B7-2 on Raji cells were analyzed by flow cytometric assay. It was observed that compared to hCGbeta or C3d3 protein, hCGbeta-C3d3 up-regulated both B7-1 and B7-2 expression on the Raji cells, and the effect was in a dose-dependent manner. The up-regulation effect was blocked efficiently by anti-CD21 mAb. The results showed that molecular adjuvant C3d may up-regulate both B7-1 and B7-2 expression on Raji cell via C3d/CD21/CD19 complex, thus enhance the antigen presentation of B cell, and the interaction between B cell and T cell.