Blast Cells and Myeloblasts Overview

Blast cells are immature cells known as precursor or stem cells. Blasts give rise to all kinds of different specialized cells. For example, neuroblasts give rise to nerve cells. Myeloblasts are immature white blood cells that develop in the bone marrow.

We all have blasts. Each of us started out as a blast or, more precisely, a blastocyst (a jumble of cells that divides enough times to become an embryo). When different types of blasts appear in unexpected places, however, or when abnormal blasts develop, they can be an indicator of cancer or another disease.

This article discusses blasts and myeloblasts, how they form, and the conditions that affect them.

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 life span, 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

Myeloblasts aren't typically found in the circulating blood of healthy people. When found in the blood, they can be an important indicator of diseases such 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.

Acute Myelogenous Leukemia

AML is a type of cancer that goes by several other names, such as acute myeloid leukemia, acute myelocytic leukemia, acute myelogenous leukemia, acute granulocytic leukemia, or acute non-lymphocytic leukemia. It is most common in older people.

AML happens when blasts don't mature and build up in your bone marrow. When the production of these blasts gets out of hand, they can spill from the bone marrow into circulating blood. Their presence on a complete blood count (CBC) test is very suspicious for leukemia.

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 cancers 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.

MDS progresses to AML in about one in three people. Treatments like bone marrow transplants or certain medications can help slow or prevent this progression.

When to See a Healthcare Provider

While the symptoms of AML and MDS are often nonspecific in the early stages, you should see a doctor if you experience:

• Prolonged bleeding
• Easy bruising
• Persistent fatigue
• Frequent infection
• Unexplained weight loss of 5% or more

Summary

Blasts are immature cells. It is normal to have blasts, but it can be a sign of disease when they appear in places they aren't normally found.

Blasts in the blood are associated with cancers such as myelodysplastic syndromes and acute myelogenous leukemia. These conditions occur when immature blasts build up in the bone marrow and spill into the bloodstream.