Administration of intragraft interleukin-4 prolongs cardiac allograft survival in rats treated with donor-specific transfusion/cyclosporine.

It has been hypothesized that immunoregulating cytokines produced by intragraft Th-2 cells may be important for prolonged allograft survival. ACI hearts transplanted into untreated Lewis rat recipients survived for 6.2 days, but they survived for 72.1 days in recipients treated with a donor-specific transfusion and low dose CsA for 14 days. In donor-specific transfusion/CsA-treated animals, intragraft infusion of IL-10 via a 14-day osmotic minipump had no effect on graft survival (75.6 days), but intragraft infusion of IL-4 prolonged graft survival to 149.2 days (P < 0.01). While the actual mechanism of this effect is unclear, it suggests that IL-4 may be important in the development of long-term graft survival.