The invention relates to the use of adenosine to deplete alloreactive T cells from donor grafts to prevent graft-versus-host disease (GVHD). The method includes culturing donor cells that include T cells with recipient antigen presenting cells (APCs) to form a mixture of cells. The recipient’s APCs activate donor T cells. The activated T cells are treated with high doses of adenosine or an adenosine-like molecule to decrease or inhibit viability of the activated donor T-cells. The adenosine or adenosine-like molecule is filtered away from the mixture resulting in cells that can be transplanted into the recipient.