CD28 and B-cell chronic lymphocytic leukemia: Combining these tools, we were able to analyze the phenotype of populations over- or under-represented in CLL, compared to controls, within Treg cells, defined as CD25+ and CD127 low-expressing/- CD4+ T-cells, as shown in Figure 1E. Equal numbers of CD25+ CD127lo/− CD4+ T-cells from CLL patients and healthy controls were introduced in the analysis and clustered according to their level of expression of cell surface markers CD25 (IL-2Rα) and CD127 (IL-7Rα), as well as CCR7, CXCR5, CD28, CD38, CD161, CD31, CD45RA, HLA-DR, and CD15s.