CLL-PB-CD19+/CD5+ B cells are isolated from CLL peripheral blood mononuclear cells using a direct immunomagnetic CD19+ MicroBead labeling system. Available in untreated or relapsed/ refractory stages.The co-expression of CD5 is typically found on cancerous CLLCD19+ B cells. Current research is underway to identify the CLL clonal origin of CLL from this cell population. Although these cells appear mature in morphology,they are in developmental arrest. Researchers have shown that only 1% of these cells are in an active cycle. CD19+/CD5+ B cells play an important role in production of IgM autoantibodies.