Increased proportion of CD4⁺FOXP3⁺ cells in GVHD patients receiving photodepletion cells. Five patients suffering from corticosteroid-refractory GVHD underwent weekly lymphophereses. Each cell collection was exposed to photodepletion and reinfused to the patient. Patient blood samples were obtained on weeks 0, 2, 4, and 8 for flow cytometric analysis of (A) CD4⁺ cells and CD8⁺ cells and (B) FOXP3⁺ cells within the CD4⁺ subpopulation. For comparison, gray bars indicate results from 5 healthy donors (mean ± SEM). Mean ± SEM of results from 5 patients; *P < .05 and **P < .01.