The reasons for progression and autoimmune cytopenias (AIC) in chronic lymphocytic leukemia (CLL) are not entirely clear, with previous studies suggesting a role for regulatory T-cells (Treg). In this study we prospectively studied Treg (CD3+CD4+CD25highCD127low), interleukin-10 (IL-10) producing Treg and T-helper 17 (Th17) (CD3+CD4+IL-17+) cells in 40 treatment-naive patients with CLL. The percentage of Th17 and not Treg cells was significantly higher in the AIC cohort than in those without AIC (p<0.0001). The Treg:Th17 ratio was skewed in favor of Th17 in the AIC cohort (p=0.02). Th17 cells are responsible for AIC of CLL. Analysis of lymph-node aspirates showed that the percentage of Treg and IL-10 expression in Treg and not Th17 was significantly higher than in peripheral blood (p<0.01). Treg cells play a major role in the microenvironment where disease progression occurs. This shows the importance of maintaining the Treg:Th17 equilibrium, for imbalance leads to CLL progression or AIC.
Keywords: Autoimmune cytopenia; T-helper 17; chronic lymphocytic leukemia; regulatory T-cells.