Regulatory T Cells in Chronic Graft-Versus-Host Disease After Extracorporeal Photopheresis: Correlation With Skin and Global Organ Responses, and Ability to Taper Steroids.

Background: Induction of immune tolerance by an increase in regulatory T (Treg) cells after extracorporeal photopheresis (ECP) is thought to contribute to how ECP exerts its therapeutic effect in patients with chronic graft-versus-host disease (cGvHD). We investigated whether percentages and absolute counts of Treg cells changed post-ECP, and examined correlation with response.

Methods: Absolute counts and % of CD4+ T cells and Treg cells (CD4 + CD25 + FOXP3 + CD127dim/-) were evaluated using flow cytometry in 32 patients with cGvHD treated by ECP for a minimum of 3 months, and up to 12 months.