Transforming growth factor-beta/interleukin-2-induced regulatory CD4+ T cells prolong cardiac allograft survival in rats.

Background: Treatment of naive CD4+ T cells in vitro with transforming growth factor-beta (TGF-beta) or TGF-beta/interleukin-2 (IL-2), combined with stimulation in a mixed lymphoid culture (MLC), has been shown to generate CD4+ CD25+ regulatory T cells. However, little is known about the effect of these regulatory T cells on cardiac allograft survival in vivo.

Methods: CD4+ CD25+ T cells were generated from Lewis (LEW) rat spleen through a primary MLC with TGF-beta (10 ng/ml) or TGF-beta/IL-2 (10 U/ml). The effect of adoptive transfer of the CD4+ CD25+ T cells (5.0 x 10(7)) was evaluated using an animal model of ACI rat cardiac allograft survival in LEW recipients.

Results: The MLC with TGF-beta or TGF-beta/IL-2 generated CD4+ CD25+ regulatory T cells, which suppressed the cytotoxic activity of LEW spleen T cells against irradiated ACI spleen cells in vitro. Adoptive transfer of the CD4+ CD25+ regulatory T cells intravenously to naive syngeneic recipients significantly prolonged the ACI cardiac allograft survival (N = 6, 13.5 +/- 3.4 days) compared with the control group (N = 6, 5.0 +/- 0.6 days).

Conclusions: Intravenous administration of CD4+ CD25+ regulatory T cells, successfully generated by TGF-beta/IL-2 treatment, had a significant effect on cardiac allograft survival in this rat model. Adoptive transfer of regulatory T cells may represent a novel approach for preventing allograft rejection.