A method for identifying CD4+ Treg cells suitable for use as starting material in cellular immunotherapy, the method comprising i) analysing samples from target tissue A to identify CD4+ Treg cells with migratory character between the diseased tissue, collecting lymphatics, peripheral blood, distinct tissue adjacent to the diseased target tissue A and/or distinct tissue that is not vicinal though has migratory Treg communication with target tissue A, ii) optionally analysing samples from target tissue A to identify CD4 + Treg cells with immunosuppressive function in tissue A, iii) optionally analysing samples from lymphatic tissue B to identify CD4 + Treg cells with migratory character between disease draining lymphatics and non-disease draining lymphatics of diseased or non-diseased target tissue A, iv) optionally analysing samples from lymphatic tissue B to identify CD4 + Treg cells with immunosuppressive function in tissue B where the Treg cells are also emigrant from target tissue A, v) analysing samples from peripheral blood, tissue C, to identify CD4+ Treg cells with migratory character and/or immunosuppressive function where the Treg cells are also emigrant from target tissue A, vi) analysing sample(s) from tissue compartments A and/or B and C, that are analytically or physically depleted of emigrants from thymus and/or immigrants from peripheral blood to a lymph node, to restrict analyses to CD4 + Treg cells of target tissue A origin and/or tropism, to identify emigrant CD4 + Treg cell populations of target tissue A, to identify emigrant CD4 + Treg cell populations with propensity to immigrate to target tissue A, to identify a migratory and/or functional defect in the CD4+ Treg cell population identified as expressing migratory and/or functional elements specific for target tissue A in any of tissue A, B or C, and whereby a combination of surface or intracellular markers on CD4+ Treg cells is identified, which combination identifies which surface or intracellular markers should be present and which surface markers should not be present in CD4+ Treg cell populations suitable for use as starting material in cellular immunotherapy. i) analysing samples from target tissue A to identify CD4+ Treg cells with migratory character between the diseased tissue, collecting lymphatics, peripheral blood, distinct tissue adjacent to the diseased target tissue A and/or distinct tissue that is not vicinal though has migratory Treg communication with target tissue A, ii) optionally analysing samples from target tissue A to identify CD4 + Treg cells with immunosuppressive function in tissue A, iii) optionally analysing samples from lymphatic tissue B to identify CD4 + Treg cells with migratory character between disease draining lymphatics and non-disease draining lymphatics of diseased or non-diseased target tissue A, iv) optionally analysing samples from lymphatic tissue B to identify CD4 + Treg cells with immunosuppressive function in tissue B where the Treg cells are also emigrant from target tissue A, v) analysing samples from peripheral blood, tissue C, to identify CD4+ Treg cells with migratory character and/or immunosuppressive function where the Treg cells are also emigrant from target tissue A, vi) analysing sample(s) from tissue compartments A and/or B and C, that are analytically or physically depleted of emigrants from thymus and/or immigrants from peripheral blood to a lymph node, to restrict analyses to CD4 + Treg cells of target tissue A origin and/or tropism,