Regulatory T cells in chronic lymphocytic leukemia: implication for immunotherapeutic interventions.

Identification of regulatory T cells (Tregs) has led to breaking the dichotomy of the Th1/Th2 axis in the immunopathology of several diseases such as autoimmune diseases and cancer. Despite the presence of extensive information about immunobiology of Tregs in pathogenesis of autoimmune diseases, little is known about the frequency and function of these cells in hematologic malignancies, particularly chronic lymphocytic leukemia (CLL). Recent data have demonstrated increased frequency and intact functional capacity of CD4(+) Tregs in CLL patients. However, the precise role of these cells in the immunopathology of CLL is not well known. While targeting Tregs in cancer diseases seems to be an interesting immunotherapeutic approach, such therapeutic interventions in CLL might be deleterious due to suppression of the tumor-specific adaptive and innate immune responses. Thus, the precise biological and regulatory functions of all Tregs subsets should be carefully investigated before planning any immunotherapeutic interventions based on targeting of Tregs. In this communication, we review the recent data published on immunobiology of Tregs in CLL and discuss about the possibility of targeting Tregs in CLL.