Abstract: To study the immunosuppressive effect of monoclonal antibody to dendritic cell (DC McAb) on cardiac allograft rejection in rats and the variation in the cellular immunity and humoral immunity of rats caused by it in vivo. Methods: Cardiac transplantation was performed in the abdominal cavity of the recipient (Wistar→SD). Rejection was defined as the day of cessation of the transplanted heartbeat. Purified WZD (DC McAb) was diluted in saline to 1∶25(McAb25 group) or 1∶50(McAb50 group), and administered by intraperitioneal injection for 7 consecutive 1?ml/day to cardiac allograft recipients after engraftment, but for 4 or 5 consecutive 1?ml/day to untransplant SD rats. A same dose of NS was injected to the rats of NS group. Immediately upon sacrifice of rats at 5 days spleens were immunologic studied for examination of the lymphocytes proliferation, the production of interleukin2(IL2), and the levels of the antibody to SRBC. Results: The mean survival of cardiac allografts was 19.37±2.93 days in McAb25 group, 19.13±2.25 days in McAb50 group, but 8.75±1.28 days in NS group (P＜0.01). The lymphocytes proliferation and levels of IL2 produced by rat splenic lymphocytes in both McAb groups significantly decreased(P＜0.01). The levels of antibody to SRBC in rats in McAb25 group and McAb50 groups declined from 0.458±0.086 to 0.207±0.045 and to 0.221±0.049, respectively(P＜0.01). Conclusion: DC McAb could prolong the survival of rat cardiac allografts, and inhibit the splenic lymphocytes proliferation, the production of interleukin2 and the levels of the antibody to

Key words: Antibodies, monoclonal, Dendritic cells, Immunosuppressant, Allograft rejection, Heart transplantation, Rat