Extracorporeal photopheresis in refractory chronic graft-versus-host disease: The influence on peripheral blood T cell subpopulations. A study by the Hellenic Association of Hematology

Extracorporeal photopheresis (ECP) has been established as an effective treatment modality for patients with chronic extensive graft-versus host disease (GVHD). In the present study, we evaluated the influence of ECP on the numbers of CD4+, CD8+, CD20+, CD56+ cells, and on T-regulatory (Tregs), as well as on the numbers of naïve, central memory (CM), and effector memory (EM) T-cells in patients treated for refractory chronic GVHD. Flow cytometric analysis of peripheral blood lymphocytes was performed for the calculation of the different T-cell subsets. Patients with GVHD had a higher percentage of EM-CD4+ cells in comparison with healthy donors (p = 0.046). The percentages of naïve-CD8+, naïve-CD4+, CM-CD8+, CM-CD4+, EM-CD8+, and Tregs were not different between patients with GVHD and healthy donors. Similarly there was no statistical difference in the percentages of naïve, CM, and EM CD4+ and CD8+ cells before and after 3 months of treatment with ECP. However, in the subset of Tregs a statistically significant increase was observed after 3 months of treatment with ECP (p = 0.015). Responders to ECP had statistically significantly higher absolute numbers of CD4+, and CD8+ cells, in comparison with non-responders. These data further support the concept that ECP does not cause immune-suppression, but should be better considered as an immune-modulating treatment.