Downregulation of both interleukin-12 and interleukin-2 in heart allografts by pretransplant host treatment with granulocyte colony-stimulating factor and tacrolimus.

Since recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been reported to induce immune deviation, we examined the effects of pretransplant treatment of recipients with rhG-CSF on heart allograft survival. Before heterotopic heart transplantation from DA to Lewis rats, recipients were given rhG-CSF (125microg/kg s.c. twice a day from day -5 to 0) and/or tacrolimus (2mg/kg i.m. on day 0). Combined treatment with both rhG-CSF and tacrolimus prolonged graft survival significantly (P<0.05), while rhG-CSF or tacrolimus alone did not. At 24h after transplantation, cytokine mRNA levels in the grafts were measured by reverse transcription and real-time polymerase chain reaction. IL-12 p35 expression was highly inhibited by rhG-CSF treatment, but tacrolimus did not change the levels. Conversely, rhG-CSF treatment did not affect IL-2 levels, while tacrolimus completely blocked its expression. Combined pretreatment was effective for suppressing acute rejection reaction by downregulating these two key type-1 cytokines, IL-12 and IL-2, with unchanged levels of IL-10.