Effect Of FK506 Combinated With FTY720 On T-cell Subsets And Its Immune Function Following Homologous Heart Transplantation In Rats

PART 1 The model of rat heterotopic heart transplantation by modifed Heron's cuff vessel anastomosis technique.【Abstract】Objective To establish the simplified and stable model of rat heterotopic heart transplantation by modifed Heron's technique.Methods SD rat served as recipient and Wistar rat as donor.After the donor was heparinized,the heart was maked unbeated by using the Custodiol(HTK) llquor and procured in advance.The Wistar rat donor 's ascending aorta and pulmonary artery were anastomosed to SD rat recipient's right common carotid artery and external jugular vein respectively with a self-made "sleeve" anastomosis and to form the blood route.Results The donor heart was resurrected . 24 consecutive successful transplantations have been performed by single surgeon were done. All the operations were successful without death of the rats. Conclusions The model of rat cervical heart transplantation can be established successfully by using modified heron's technique.The procedure of the cervical heterotopic heart transplantation is repeatable,simple and convenient and high reproducible model.The model is very applicable for various transplantation immunological studies. PART 2 Effect of FK506 combinated with FTY720 on T-cell subsets and its immune function following homologous heart transplantation in rats【Abstract】Objective To investigate the preventive effects of FK506 combinated with FTY720 on acute rejection following homologous heart transplantation and objective explore the effect and mechanism 0f FK506 combined with the new immunosuppression FTY720 on the cardiac allograft in rats.Methods Donor's heart derived from rat was transplanted into the cervical part of another rat. On the 7th day after transplantation,CD4+,CD8+T-cell subsets and IL-2 were examined and graft's pathological changes were observed. The recipients were randomly divided into mono-FK506 therapy group,mono-FTY720 therapy group and combinated-therapy group,the un-treatment group as control. FK506 and FTY720 were administrated to recipient at 0.2 mg/kg/d and 3mg/kg/d for 7 days after operation.And the heart rate were recorded everyday .The allograft myocardium were stained with HE to observe the strength of immunologic rejection.The numbers of peripheral lymphocytes and IL-2 were determined during the course of administration by the methods of flow cytometry(FCM) and ELISA to explore the mechanism of FK506 and FTY720.Results Compared with un-treatment group, The survival of cardiac allograft were significantly prolonged in mono-therapy group(P<0.01) and graft's pathological changes were significantly mitigated in mono-therapy group; Combination-therapy of FK506 with FTY720 could significantly prolong the survival of graft heart when compared with FK506 or FTY720 used alone. The unmber of CD4+T-cell and level of IL-2 in mono-therapy group and combination-therapy group were much less than in un-treatment group. FCM indicates the numbers of peripheral lymphocytes CD4 +,CD8 + T-cells in mono-therapy group .Group combination-therapy group were decreased significantly in 7 days after operation. ELISA showed to us that the IL-2 in peripheral blood of recipient were less obviously in mono-therapy group and (FK506+ FTY720)group than in the un-treatment groups(P<0.01). Conclusions 1.Both FK506 and FTY720 can suppress proliferation of CD4+T-cell and expression level of IL-2 . 2.In cell immumity process of acute rejection, CD4+T-cell was activationed first and delivery IL-2 cell factor and so on, then CD8+ T-cell multiplicated and differentiated to effector cell. 3.The prospect of combination of the two drugs for immunologic rejection is very bright and so they can prevent or delay acute rejection.