Fig. 1

PegINFα increases Treg and highly suppressive Treg cells in peripheral blood of PV and ET patients. PBMC were collected from patients with PV or ET treated with PegINFα or HU for at least 70 days (range 70–616, median 112 for PegINFα and range 113–2422, median 175 for HU treated patients). Lymphocytes were analyzed by flow cytometry using surface markers, CD3, CD4, CD25, CD39, HLA-DR and intracellular markers Foxp3, Ki-67 and Helios. a represents CD4⁺ CD25⁺ Foxp3⁺ Treg cells. In b the frequency of Treg was analyzed at different time points after initiation of PegINFα treatment. c–e show frequency of Ki-67⁺ Treg, Helios⁺ Treg, and CD39⁺/HLA-DR⁺) Treg