What Are Blast Cells and Myeloblasts?

High cell counts may be an indication of disease

Red Blood Cells

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In biology and in medicine, the suffix "-blast" refers to immature cells known as precursor cells or stem cells. You can have blasts that give rise to all kinds of different specialized cells. For example, neuroblasts give rise to nerve cells and angioblasts give rise to fat cells. Just as nerve and fat cells develop from immature precursor cells, blood cells also come from immature blood-forming cells, or blasts, in the bone marrow. Blood cells are continually formed to replace those that have become old or worn out. 

So, why is it important to know about blast and, in particular, bone marrow blast cells?

We all have blasts. In fact, we started out as a blast or, more precisely, a blastocyst (the jumble of cells that divide enough times to become an embryo). What is key to know is that the appearance of different types of blasts in unexpected areas of the body or the development of abnormal blasts can be an indicator of disease or cancer.

Bone Marrow Blast Cells 

In healthy bone marrow, blood-forming cells known as hematopoietic stem cells develop into red blood cells, white blood cells, and platelets through a process called hematopoiesis. This process occurs throughout your entire lifespan. The stem cell chooses its path of development into one of two cell lines, the lymphoid cell line or the myeloid cell line.

In the myeloid cell line, the term "blast cell" refers to myeloblasts or myeloid blasts. These are the very earliest and most immature cells of the myeloid cell line.

Myeloblasts give rise to white blood cells. This family of white blood cells includes neutrophils, eosinophils, basophils and monocytes, and macrophages.

Although the myeloid cell line accounts for around 85 percent of the cells in bone marrow, less than 5 percent should be comprised of blast cells. Anything more may be an indication of a serious disease.

In fact, the presence of these circulating myeloblasts can be an important indicator of such diseases as acute myelogenous leukemia and myelodysplastic syndromes.

Myeloblast Disorders

In the case of acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS), there is an overproduction of abnormal myeloblasts. These cells are unable to develop further into mature white blood cells.

AML is a type of cancer that goes by several other names, such as acute myelocytic leukemia, acute myelogenous leukemia, acute granulocytic leukemia, or acute non-lymphocytic leukemia. It is most common in older people. Most cases of AML develop from cells that would turn into white blood cells other than lymphocytes, however, some cases of AML develop in other types of blood-forming cells.

MDS is a group of disorders that affect the production of new blood cells in the bone marrow. In these diseases, the bone marrow produces abnormal blast cells that fail to mature properly and are unable to function. These abnormal blasts begin to take over the bone marrow and prevent the production of adequate numbers of other types of blood cells, such as platelets, red blood cells, and healthy white blood cells. In fact, production of leukemic blasts may get so out of hand that the immature cells spill out from the bone marrow into the circulation.

The presence of blast cells on a complete blood count (CBC) is therefore very suspicious for leukemia. Blast cells are not typically found in the circulating blood of healthy individuals.

When to See a Doctor

While the symptoms of AML and MDS are often non-specific in the early stages, you should see if a doctor if you experience prolonged bleeding, easy bruising, persistent fatigue, frequent infection, or unexplained weight loss of 5 percent or more.

What Is Refractory Anemia With Excess Blasts?
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Article Sources
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