Aqueous extract of Caesalpinia sappan decelerates allograft rejection by inducing imbalance between CD4(+) CD25(+) T cells and Th17 cells.

Objective: Aqueous extract of Caesalpinia sappan (CSE) has immunosuppressive activities, but the mechanism remains unknown. This study was to investigate the effect of CSE on the balance between CD4(+) CD25(+) T cells and Th17 cells.

Methods: Allografted Balb/c recipients were intraperitoneally treated with CSE for 14 continuous days, and the graft survival was observed. The spleen cells and peripheral blood of the recipient mice were harvested for phenotyping by flow cytometry, detection of gene expression by real-time PCR and cytokine detection by ELISA.

Results: CSE prolonged skin allograft survival, increased the percentage and number of CD4(+) CD25(+) T cells, the expression of Foxp3 and STAT5 in spleen cells, the serum levels of IL-10 and TGF-β1, whereas reduced the percentage and number of Th17 cells and serum IL-17 level in Balb/c recipients.

Conclusion: CSE expanded CD4(+) CD25(+) T cells and decreased Th17 cells in vivo thereby improving skin allograft survival in mice, indicating that CSE affects the balance between CD4(+) CD25(+) T cells and Th17 cells in the graft to induce rejection.