Blood cells (hematopoiesis) form from the bone marrow of flat bones. These hematopoietic stem cells give two lines. The myeloid line differentiates into red blood cells, platelets, monocytes and polymorphonuclear cells. The lymphoid line is differentiated into T lymphocytes, B lymphocytes. In this drawing, indicate which immune cells are affected during chronic lymphocytic leukemia (cancer of the stem cells which make blood in the bone marrow): hematopoietic stem cells, the lineage lymphoid, including B lymphocytes