Tregs and GvHD prevention by extracorporeal photopheresis: observations from a clinical trial
Roberto Crocchiolo, Clara Cesana, Debora Girgenti, Giambattista Bertani, Claudia Barba, Giuseppa Liga, Ursula Ferri, Lara Crucitti, Giovanni Grillo, Silvano Rossini, Roberto Cairoli
Abstract
The aim of the present study was to evaluate the circulating T regulatory cells (Tregs) in patients undergoing extracorporeal photopheresis (ECP) for the prevention of chronic graft-versus-host disease (GvHD) and to search for any correlation between Tregs counts and chronic GvHD occurrence. Among n = 12 patients with complete longitudinal data, the median cumulative values of absolute peripheral Tregs counts were 21.64 and 63.49 cells/µL for patients who developed chronic GvHD and those who did not develop it, respectively (p = 0.05). The analysis of the median absolute counts of peripheral HLA-DR + Tregs provided similar results, showing that 20% (1 out of 5) and 100% (7 out of 7) of patients with HLA-DR + Tregs values of > 5 cells/µL were in the GvHD and non-GvHD groups, respectively (p = 0.01). In conclusion, the present results support the involvement of Tregs in the prevention of chronic GvHD in patients receiving ECP and suggest Tregs count as a potential biomarker of ECP effectiveness. Future strategies are needed to enhance Tregs expansion and/or activity in conjunction with ECP for an effective chronic GvHD prevention.