Effects of FTY720 on peripheral blood lymphocytes and graft infiltrating cells in a rat model of chronic renal allograft rejection.

AIMS: Chronic renal allograft loss is still an unsolved problem in kidney transplantation. We evaluated the impact of FTY720, a S1P receptor agonist, known to deplete lymphocytes from the peripheral blood by sequestering them into lymph nodes and Peyer's patches, on blood lymphocytes and graft infiltrating cells in a rat model of chronic real allograft rejection.

METHODS: LEW rats served as recipients for LEW.1U7B kidney grafts. All animals were treated with CsA (5mg/kg) for 10 days after renal transplantation and monitored for kidney function, peripheral blood lymphocytes and graft infiltrating cells. In the intervention group (n=7) FTY720 therapy was started 7 weeks post-KTx in a dose of 0.5 mg/kg p. o. three times a week.

RESULTS: In the control group the survival of the rats was 9, 11, 18 and 4 × 24 weeks, in the intervention group 2 × 8, 9, 2 × 11, 18 and 20 weeks. While in the intervention group the number of T- and B-lymphocytes in the peripheral blood was successfully reduced during FTY720 treatment, both groups showed significant amounts of T- and B-lymphocytes in the kidney grafts. Animals in both groups developed donor specific antibodies, extensive albuminuria and severe chronic changes in the grafts.

CONCLUSIONS: FTY720 was highly effective to reduce T- and B-lymphocytes in the peripheral blood, but not effective in clearing their infiltration in the graft. Graft survival was not prolonged by FTY720 treatment starting late after kidney transplantation.