When the test was performed in the presence of mitogen stimulating lipopolysaccha-rides (LPS), phytohaemagglutinin (PHA), concanavalin A (ConA) and alloantigen
, a concentration dependent inhibition of lymphocyte proliferation was observed.
In vivo exposure of CD4+CD25+T cells from normal naive mice to alloantigen
in a T cell-deficient environment elicits spontaneous expansion of alloantigen
-specific CD4+CD25+natural Treg cells, which are able to suppress allograft rejection mediated by subsequently transferred naive T cells, leading to long-term graft tolerance.