The T cell activation marker CD150 can be used to identify alloantigen-activated CD4+25+ regulatory T cells

We have been investigating whether alloantigen-specific CD4(+)25(+) regulatory T cells can be identified for use in treating graft-versus-host disease. CD 150, which is upregulated on the surface of all activated T lymphocytes, was identified as a candidate marker for alloantigen-activated CD4(+)25(+) regulatory T cells by gene chip analysis. Freshly isolated CD4(+)25(+) cells had only low cell-surface expression of CD150. comparable to that of CD4(+)25(-) T cells. Increased CD150 expression was observed on all T cells after coculture with allogeneic stimulator cells. When Purified CD4(+)25(+) cells were precultured with allogeneic stimulator cells, then sorted into CD150(+) and CD150(-) subsets, allosuppressive activity was contained primarily in the CD150(+) fraction. These cells also suppressed the proliferation of alloantigen-activated autologous T cells, and they could be expanded in vitro without loss of their suppressive capacity. These results suggest that CD150 can be used as a marker for the identification of purified alloantigen-activated CD4(+)25(+) regulatory T cells. (C) 2004 Elsevier Inc. All rights reserved.