n WHAT IS LEUKEMIA? Leukemia is a cancer of the blood and bone marrow. The bone marrow is the soft, spongy tissue found inside of bones where normal blood cells are made. The blood cells that are made in the bone marrow include the white blood cells (WBCs), red blood cells (RBCs), and platelets. Each type of blood cell has its own job in the body. WBCs are the infection-fighting cells. RBCs provide oxygen and energy to the body. Platelets help blood to clot (or thicken); the blood’s ability to clot is important during certain situations, such as when you have a cut. Leukemia occurs as a result of abnormal growth of immature blood cells. These cells are called blast cells . These immature cells grow out of control, crowd out the normal cells (WBCs, RBCs, and platelets) in the bone marrow, and eventually spill out into the bloodstream. As a result, leukemia may be found in other parts of the body such as the lymph nodes, liver, spleen, central nervous system (which is the brain and spinal cord), testicles, skin, and other organs.
Bone Marrow The bone marrow is where blood cells and the immune system develop. Bone marrow produces stem cells, which are the cells that all of our blood cells come from; sometimes they are called “mother” cells. Stem cells mature into two different types of cells: lymphoid cells or myeloid cells. Lymphoid stem cells further develop into lymphocytes. These cells make up the body’s immune system, which is important in fighting infection and attacking cancer cells. Myeloid cells further develop into RBCs, platelets, or other types of WBCs called granulocytes . Leukemia occurs in cells that develop from either the lymphoid or myeloid cell line.
White Blood Cells (WBCs) WBCs, also called leukocytes , help to defend the body against infections. Infections can be caused by bacteria, viruses, and fungi. The three different types of WBCs are lymphocytes, granulocytes, and monocytes. Lymphocytes are a type of WBC that develop from the lymphoid cell line and help to fight infections. The three types of lymphocytes are B lymphocytes (B cells), T lymphocytes (T cells), or natural killer cells (NK cells). B cells and T cells help the body by developing antibodies to fight infection. NK cells fight viruses and attack cancer cells. Granulocytes are a type of WBC that develop from the myeloid stem cell. They help destroy infections caused by bacteria. Monocytes are a third type of WBC that are related to granulocytes. Monocytes help fight against bacteria by sur- rounding and digesting them. They also help lymphocytes identify germs.
Red Blood Cells (RBCs) RBCs carry oxygen to all of the cells in the body. If the number of RBCs is low, a child may look pale and feel tired
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