Photodepletion (PD) preserves functional Tregs. (A) CD4⁺CD25⁻ cells from healthy donors were cultured with allogeneic MHC-mismatched cells for 5 days either alone or in the presence of autologous untreated (untx) or photodepletion-treated CD4⁺CD25⁺ cells (Tregs) from autologous donors. Proliferation was evaluated by measuring ³H-thymidine incorporation (mean ± SEM; n = 5). (B) PHA-activated PBMCs from healthy donors were exposed (or not) to photodepletion and admixed with autologous PHA-activated PBMCs. Three days later, CD4 and CD8 cell proliferation was determined by flow cytometry using EdU incorporation. Plot shown is representative of 3 independent experiments **P < .01 and ***P < .001