Astragalus membranaceus injection delayed allograft survival related with CD4+ CD25+ regulatory T cells.

INTRODUCTION

Recently it has been reported that Astragalus membranaceus injection (AMI) inhibits immune responses, but whether it affects alloimmunity is not clear. It has been shown that the CD4(+) CD25(+) regulatory T cells (Treg) down-regulate immune responses. The aim of our study was to investigate the effects of AMI on allograft survival and its relation to Treg.

MATERIALS AND METHODS

Allografted mice were administered AMI for 14 consecutive days with observations of graft survival. The specific recall response, the ratio of Treg, the expression of Foxp3 mRNA, and interleukin (IL)-10 secretion were measured by mixed lymphocyte reactions (MLR), FCM, reverse transcriptase-polymerase chain reaction, and radioimmunoassay, respectively.

RESULTS

AMI significantly prolonged allograft survival by up-regulating the Treg ratio and promoting Foxp3 expression (P < .05). The ratio of Tregs, the expression of Foxp3 mRNA, and the IL-10 level in the AMI administration group increased from day 7, to reach a maximum at day 14, recovering to the initial level on day 21. No obvious difference was detected between the AMI and a cyclosporine group.

CONCLUSION

AMI administered in vivo prolonged allograft survival associated with promotion of Treg activities.