Blast Cells and Myeloblasts Overview

High Cell Counts May Be an Indication of Disease

In biology and in medicine, the suffix "-blast" refers to immature cells known as precursor cells or stem cells. Blasts give rise to all kinds of different specialized cells. For example, neuroblasts give rise to nerve cells. Blood cells come from blasts in the bone marrow.

We all have blasts. In fact, we started out as a blast or, more precisely, a blastocyst (a jumble of cells that divides enough times to become an embryo).

However, when different types of blasts appear in unexpected areas, or when abnormal blasts develop, they can be an indicator of cancer or other disease.

Red Blood Cells
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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, as blood cells are continually formed to replace those that have become old or worn out. The stem cell chooses its path of development into one of two cell lines, lymphoid or myeloid.

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
  • Macrophages

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

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

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.

Acute Myelogenous Leukemia

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.

Myelodysplastic Syndromes

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.

If the production of leukemic blasts gets out of hand, they can spill from the bone marrow into circulating blood. Blast cells aren't typically found in the circulating blood of healthy people, and their presence on a complete blood count (CBC) test is very suspicious for leukemia.

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
  • Unexplained weight loss of 5% or more
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Article Sources
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  1. Hematopoietic Stem Cells. Stem Cell Information. Chapter 5. National Institutes of Health.

  2. Duong VH, Padron E, Al ali NH, et al. The prognostic value of circulating myeloblasts in patients with myelodysplastic syndromes. Ann Hematol. 2018;97(2):247-254.doi: 10.1007/s00277-017-3186-4

  3. Adult Acute Myeloid Leukemia Treatment: Patient Version. 2019 Jul 23. Adult Treatment Editorial Board. PDQ Cancer Information Summaries [Internet]. Bethesda (MD): National Cancer Institute (US); July 23, 2019

  4. Myelodysplastic syndromes. National Institutes of Health. Genetic and Rare Diseases. 8/16/2017

  5. Tests for Acute Myeloid Leukemia (AML). American Cancer Society. August 21, 2018

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