Coexpression of CD49b and LAG-3 identifies human and mouse T regulatory type 1 cells

Type 1 regulatory (Tr1) T cells are characterized by their immunosuppressive activity and cytokine secretion profile; however, their isolation and enumeration are limited by the absence of specific markers. Here Richard Flavell, Maria-Grazia Roncarolo and colleagues report that CD49b and LAG-3 are coexpressed by human and mouse Tr1 cells. These markers can be used to isolate Tr1 cells in vitro and in vivo and can be used to quantify Tr1 cells in tolerant subjects.