SELL and graft versus host disease: Previous murine studies showed that homing of adoptively transferred Tregs to secondary lymphoid organs is a prerequisite for their ability to inhibit the expansion of alloreactive T cells and that only the CD62L+ subpopulation of Tregs prevents lethal GVHD.[16, 18] Our findings confirm the tight connection between CD62L expression, homing to lymphoid tissues and protection from GVHD.