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Leukemia

  • Posted: 12/23/2013

Normal Blood Cells

To understand how leukemia affects blood cells, it helps to know about normal blood cells.

All blood cells come from blood stem cells. Although some blood stem cells are in the blood, most are in the bone marrow. Blood stem cells produce three kinds of blood cells:

  • Red blood cells: Red blood cells carry oxygen all over the body.
  • Platelets (PLAYT-lets): Platelets help form blood clots to slow or stop bleeding.
  • White blood cells: White blood cells help fight infection.

When blood cells become old or damaged, they die, and the blood stem cells produce new blood cells to take their place.

Normal Myeloid and Lymphoid Cells

The picture on page 2 shows that all blood cells are produced by blood stem cells. The picture shows two pathways. A blood stem cell can produce both myeloid stem cells and lymphoid stem cells:

  • Myeloid cells: A myeloid stem cell can produce red blood cells and platelets. Or, it can produce myeloblasts. (A blast is a type of immature cell.) Myeloblasts can produce several types of white blood cells known as granulocytes.
  • Lymphoid cells: A lymphoid stem cell can produce lymphoblasts, which can produce several types of white blood cells that are different from granulocytes.
Normal Blood Cells
All blood cells are produced by blood stem cells. The myeloid pathway leads to red blood cells, platelets, and white blood cells, and the lymphoid pathway leads to different types of while blood cells.