CD5 and B-cell chronic lymphocytic leukemia: To test the hypothesis, we isolated peripheral blood PBMC from the peripheral blood of subjects with CLL; the majority of peripheral blood mononuclear cells (PBMC) from the subjects we recruited are CD5+CD19+ leukemic B cells (Fig. 1b), ranged between 82.6 and 95.6 % with an average of 87.8 %.