CLL-PB-CD19+/CD5+ B cells are isolated from CLL bone marrow mononuclear cells using a direct immunomagnetic CD19+ Micro- Bead labeling system. Available in untreated or relapsed/refractory stages.CD5 co-expression on BM-CD19+ B Cells can be used as a strong indicator of CLL infiltration in the bone marrow. In many untreated or lower-staged CLL cases,the co-expression level of CD5 in BM-CD19+ cells is significantly lower than the co-expression level within peripheral blood.