Extracorporeal photopheresis as an antirejection prophylaxis in kidney transplant recipients: preliminary results

Extracorporeal photopheresis (ECP) is considered a promising immunomodulatory therapy of acute allograft rejection in organ transplantation and graft-versus-host disease. Our aim was to investigate the biological responses of 10 patients who underwent kidney transplantation with ECP as prophylactic treatment. They received conventional immunosuppressive therapy plus ECP immediately after transplantation: 12 to 16 applications over the course of 2.5 months. ECP procedures were performed using an automated system for leukocyte separation and photoactivation with methoxsalen. All recipients were followed by estimated glomerular filtration rate (eGFR) and peripheral T, B, natural killer, T-regulatory (Treg) and dendritic cells (DC) counts and phenotypes. An acute rejection episode appeared in one control group recipient. The ECP group showed a positive trend to an higher GFR at months 3 (53±11 vs 47.1±9; P=.17) and 6 (67.5±10 vs 53.6±3; P=.03, Wilcoxon test). An increased percentage of Treg (CD3+ CD4+ CD25+) among the total CD3 cell count (4.9%±1% to 9.4%±15%) as well as inducible Treg (CD3+ CD8+ CD28-) was observed among CD3 cells (3.3%±3% to 11.8%±8%, P=.025) within 3 months of ECP treatment. A significant difference in the percentage of Treg was noted at month 3 (completed ECP) between the ECP and the control groups (9.4%±15% vs 3%±1%; P=.01). Addition of ECP to standard immunosuppression was associated with a significantly higher GFR at 6 months and with a significant increase in natural Treg among CD3 cells.