The invention relates to the use of the 4-1BB receptor for identifying and/or separating specific regulatory Th cells after activation with an antigen, polyclonal regulatory Th cells after polyclonal activation and to a method for the identification and/or separation of regulatory Th cells, the regulatory T cells being detected on the basis of the expression of the 4-1BB receptor by an antibody, an antigen or ligands which are coupled to a fluorescent substance, haptenes or magnetic microparticles. The invention also relates to a kit comprising an antibody, an antigen or ligands for detecting the 4-1BB receptor for the identification and/or separation of a regulatory Th cell, the antibody being coupled to a fluorescent substance, haptenes or magnetic microparticles.