Th17 and Foxp3(+) T regulatory cell dynamics and distribution in myelodysplastic syndromes.

Foxp3(+) T regulatory cells (Tregs) and Th17 cells accumulate synchronously at tumor sites during cancer progression, where their interplay is apparently affecting the efficiency of the antitumor response. In myelodysplastic syndromes, a hematopoietic malignancy of myeloid origin, Tregs are highly increased in the late stages of the disease (L-MDS), but the mechanisms driving Treg expansion and the interaction between Treg and Th17 cell dynamics are still unknown. We demonstrate that the proliferative capacity of Tregs is deficient during the early MDS stages (E-MDS), while in L-MDS it returns to normal levels. In addition, synchronously to Treg expansion, L-MDS patients exhibit increased numbers of functionally competent bone marrow IL-17(+) and FOXP3(+)/IL-17(+) cells, in contrast to E-MDS patients, where Th17 cells are significantly decreased and hypofunctional. Our findings suggest similar kinetics of Treg and Th17 cells between MDS and solid tumors, indicating a common immune pathogenetic pathway between diverse cancer types.