Increased Frequency of CD8+ and CD4+ Regulatory T Cells in Chronic Lymphocytic Leukemia: Association with Disease Progression.

Little is known regarding the immunobiology of regulatory T (Treg) cells in hematopoietic malignancies, particularly in chronic lymphocytic leukemia (CLL). In the present study, we showed that the frequencies of CD8+ and CD4+ Treg cells were significantly increased in progressive as compared with indolent CLL patients and normal subjects. Enriched CD4+ Treg cells induced a similar level of inhibition in polyclonally activated B cells and effector T cells from CLL patients and normal subjects. Our results suggest that the increase in circulating Treg cells may result in downregulation of tumor-specific immune response, leading to tumor expansion and disease progression. [ABSTRACT FROM AUTHOR]