Figure 7. Positive selection and functional testing of four different Treg subsets within the total CD4⁺CD127^low+/−CD25⁺-Treg pool.

A: Magnetically isolated CD4⁺CD127^low+/−CD25⁺-Treg cells were stained with anti-HLA-DR and anti-CD45RA specific monoclonal antibodies and sorted into a population of DR^high+CD45RA⁻-, DR^low+CD45RA⁻-, DR⁻CD45RA⁻-, and naïve DR⁻CD45RA⁺-Treg cells. Subsequently the different Treg populations obtained from six different healthy non-transplanted volunteers were analyzed concerning their maximum suppressive activity (Treg/Tresp = 1/1) (B) and the minimum ratio of Treg/Tresp (titer) up to which the purified Tregs could be diluted to achieve a minimum suppressive activity of at least 15% (C).