Fig. 1.

Original dataset. CD137⁺ alloantigen-expanded Tregs (green) are more suppressive than polyclonal Tregs (red), non-enriched Tregs (blue) and CD137^neg alloantigen-expanded Tregs (purple). (A) CD137 expression upon alloantigen stimulation of flow-sorted CD4⁺CD25⁺CD127^lo human Tregs. Tregs were stimulated with immature dendritic cells (iDCs) at a cell-to-iDC ratio of 4:1. Cells were assessed for CD137 expression by flow cytometry. Data from 9 healthy human donors are shown. (B) Experimental schematic for in vitro expansion of polyclonal and alloantigen expanded Tregs created with BioRender.com (C) Suppression assays were performed using 3H-thymidine incorporation; responder cells were stimulated with allogeneic iDCs. Polyclonally expanded, alloantigen-expanded non-CD137 enriched, alloantigen-expanded enriched CD137⁺ and CD137^neg Tregs were titrated into the culture. Responders alone were used as a negative control. Responders with alloantigen were used as a positive control. Six days later, thymidine was added to the culture and after 16 h of incubation cells were harvested. Data are represented as mean +/-SD, statistical analysis was performed using unpaired t-tests (*p < 0.05, **p < 0.01, ***p < 0.001). Representative data from one donor out of five is shown.