When Blood Cells Don't Form Normally

Overview

Your body makes new blood cells every day. Sometimes these cells do not mature the way they should, and the body makes too many, too few, or the wrong kinds of blood cells. This can cause health problems, including some types of cancer.

How Blood Cells Normally Mature

Blood cells start as stem cells in the bone marrow. When an old blood cell dies, the body signals that it needs a replacement. A stem cell picks up the signal and matures into exactly the type of blood cell that is needed. It follows one of two pathways:

• Myeloid pathway — to become a red blood cell, a platelet, a granulocyte or a monocyte.
• Lymphoid pathway — to become a lymphocyte: a B cell, T cell or natural killer (NK) cell.

Some blood cancers and other blood disorders are named for the pathway involved. Partway along a pathway, the cell is no longer a stem cell but not yet mature; at this step it is called a blast cell. A myeloblast is a young cell on the myeloid pathway, becoming a granulocyte or monocyte. A lymphoblast is a young cell on the lymphoid pathway. Some leukemias happen when cells stay stuck in the blast stage. A cell that matures fully does its job until the end of its life span, then dies.

Why Blood Cells May Fail to Mature

• Bone marrow failure — the marrow cannot make enough healthy cells, because of an inherited condition or exposure to radiation or some chemicals.
• Bone marrow infiltration or replacement — something crowds into the marrow and pushes out healthy cells, as with some cancers or myeloproliferative conditions.
• Bone marrow suppression — the marrow works more slowly than normal, sometimes because of inflammation, infection or some medicines, including chemotherapy.
• Nutrition problems — the marrow needs nutrients such as protein, iron, vitamin A, vitamin B12 and folate, copper and zinc. Without enough of them, it cannot make the cells the body needs.

Problems This Can Cause

Infections: if white blood cells do not develop properly, the body cannot fight germs well. Blood disorders: too few cells cause leukopenia or neutropenia (low white cells), anemia (low red cells) or thrombocytopenia (low platelets); too many abnormal cells can lead to myelodysplastic syndromes, clotting disorders and leukemia. Cancer: abnormal blood cell formation can lead to cancer, most often blood cancers such as myelodysplastic syndromes, leukemia, lymphoma and multiple myeloma.

Questions to Ask Your Doctor

• Which of my blood counts are too high or too low, and what does that mean?
• Is the problem with how my blood cells mature, and is it on the myeloid or the lymphoid pathway?
• Do I need a bone marrow test to find the cause?
• Could a medicine I take, or a lack of a nutrient, be affecting my bone marrow?
• How can I lower my risk of infection while my white blood cell count is low?

Learn More

See the American Cancer Society's 3D tour of blood cells and bone marrow, and the Blood Cancer, Leukemia, Lymphoma, Multiple Myeloma and Myelodysplastic Syndromes groups in this category.

Source: https://www.cancer.org/cancer/understanding-cancer/what-is-cancer/blood-cell-formation.html