Regulatory T cells (TREGS) help to control the immune response. They are one factor that restrains autoimmunity and they also suppress the body's response to cancer. a paper in Leukemia Research has looked at TREGS in CLL by enumerating cells that are CD4+, CD25 bright, CD127 dim cells in the peripheral blood in 80 cases of CLL and 40 controls.
The authors found high levels of TREGS in CLL compared with controls and most increased in advanced cases (Rai 3 and 4). There was correlation with absolute B cells number and with CD38+ B cells, but not with IGHV status, ZAP-70 status or karyotype. In two patients with AIHA very low levels of TREGS were found (something I predicted 15 years ago).
Recently it has been shown that the expansion of TREGS in CLL is not due to stimulation by a tumor antigen. It may be that stimulation of the CD27-CD70 interface in proliferation centers promotes proliferation of TREGS and also decreases their sensitivity to apoptosis..
Higher frequencies of TREGS correlates with decreased T-cell responses to viral antigens, TREGS are reduced by treatment with fludarabine and Revlimid, but treatment of ITP with rituximab increases them.