Downregulation of interleukin-12p35 and upregulation of interleukin-12p40 mRNA expression in heart allografts by blood transfusion from granulocyte colony-stimulating factor-treated donors

Pretransplant treatment of recipients with recombinant human granulocyte colony-stimulating factor (rhG-CSF, 250 μg/kg/day s.c. for 5 days) facilitates heart allograft acceptance in tacrolimus-treated rat recipients. We examined effectiveness of transfusion of in vivo rhG-CSF-treated blood since rhG-CSF induces immunoregulatory cells in human blood. DA heart grafts were transplanted into tacrolimus (2 mg/kg i.m. on day 0)-treated Lewis recipients. Although graft survival prolongation by blood transfusion on day 0 from rhG-CSF-treated syngeneic Lewis was comparable to that in directly rhG-CSF-pretreated recipients ( p=0.22), transfusion of rhG-CSF-treated allogeneic DA blood was much more effective ( p=0.0016). Intragraft cytokine mRNA levels were measured by reverse transcription and real-time polymerase chain reaction at 24 h after transplantation. IL-12p35 expression was downregulated by both treatments. Notably, IL-12p40 was upregulated by rhG-CSF-treated DA blood transfusion but downregulated by transfusion of rhG-CSF-treated isogeneic blood. Differential expression of IL-12 subunits was associated with facilitation of graft acceptance by rhG-CSF-treated donor blood transfusion.