[Mesenchymal stem cells inhibit the expression of CD25 on phytohaemagglutinin-activated lymphocytes]

To investigate the regulatory effects of rat mesenchymal stem cell (MSC) on T lymphocyte proliferation by examining the early activated markers such as CD25 and CD69.

MSC had been isolated and expanded in vitro. Then it was identified by cell morphology, membrane phenotype, and differentiation potential. Nylon wool column was applied to purify T-lymphocytes. MSCs and T-lymphocytes were cultured together and were stimulated by phytohaemagglutinin (PHA), and then the expressions of CD25 and CD69 were assessed. The levels of TGF-beta1 and IL-10 in the supernatants of MSC cultures were detected by using ELISA.

(1) The expression of CD25 is suppressed in a dose-dependent manner when the T-lymphocytes are co-cultured with 10,000 MSCs or more, while 100 MSCs have no detectable effect; (2) The suppression of CD25 can be lasted more than 96 hrs; (3) The down regulation of CD25 is mediated by some soluble factors; (4) The reduced expression of CD25 caused by MSC inhibition is not mediated by TGF-beta1 and IL-10.

MSCs have significant immune regulatory effects on PHA-stimulated T-lymphocyte culture. It might provide a remarkable immune suppression in organ-transplantation to achieve better outcome in the near future.