The present invention relates to a method, in particular an in vitro method, for identifying certain immune cells of a mammal, comprising analyzing the methylation status of at least one CpG position in the gene CCR6 and/or BLR1 or an orthologous or paralogous gene thereof, and the use of DNA-methylation analysis of the genes of the proteins CCR6 and/or BLR1 for a detection and quality assurance and control of certain immune cells. In particular, the present invention relates to analyzing the methylation status of at least one CpG position in the gene CCR6 in T cells. Furthermore, the present invention relates to a kit for performing the above methods, as well as to respective uses.