Effects of different dose of FTY720 on lymphocyte cell cycle arrest in cardiac transplantation model of rats

To probe into immunosuppressive effect and cell cycle arrest effect of different dose of FTY720.we study immunosuppressive effect and cell cycle arrest effect of different dose of FTY720 and time and dose dependence of FTY720 with control and random method in vivo, respectively.(i) survival time of graft in rat cardiac transplantation model is prolonged in group treated with FTY720. It is longer in group treated with FTY720 10 mg/kg than that in group treated with FTY720 2 mg/kg. (ii) The mean sum of lymphocyte in periphery blood decrease obviously 2 h after administration, reaches its peak 4 h after administration, and then maintain at low level stably. The mean sum of lymphocyte shows a linear relationship with dose of FTY720 and decrease with increasing of dose of FTY720. (iii) The percent of cell in G1-G0 increased in group treated with FTY720, not only in thymus but also in lymph node; this is more prevalent in the group treated with FTY720 10 mg/kg than that in group treated with FTY720 2 mg/kg. Similarly, the percent of cell in S and G2-M decreased in group treated with FTY720, not only in thymus but also in lymph node, and this decrease is more associated with group treated with FTY720 10 mg/kg than the one treated with FTY720 2 mg/kg.FTY720 is an effective immunosuppressant and immunosuppressive effect of FTY720 show a tendency of time and dose dependent. Effect of cell cycle arrest of FTY720 is related to dose of this new immunosuppressant.