What's in Your Blood—and What Does It Have to Do With Myeloma?

 

Before we can really understand multiple myeloma, it helps to understand what is happening inside our blood and bone marrow.

Blood may look like one simple red liquid, but it is actually made up of several different components, each with an important job.

What's in Blood?

Blood contains four major components:

Red blood cells carry oxygen from the lungs throughout the body and bring carbon dioxide back to the lungs. When myeloma interferes with the production of red blood cells, anemia can develop, causing fatigue, weakness, and shortness of breath.

White blood cells are part of the immune system and help protect the body against infections.

Platelets help the blood clot and control bleeding.

Plasma is the pale yellow liquid portion of blood. It makes up more than half of our blood and carries blood cells, proteins, nutrients, hormones, antibodies, electrolytes, and waste products throughout the body.

But here's where myeloma can get a little confusing.

Plasma Isn't the Same as a Plasma Cell

Despite their similar names, plasma and plasma cells are two different things.

Plasma is the liquid part of your blood.

Plasma cells are specialized white blood cells that develop from B lymphocytes and are found primarily in the bone marrow. Their job is to produce antibodies—also called immunoglobulins—that help protect us from infection.

And plasma cells are where multiple myeloma begins.

Antibodies and Myeloma

Healthy plasma cells make antibodies that recognize and help fight bacteria, viruses, and other threats.

Antibodies contain heavy chains and light chains. The five major heavy-chain classes are IgG, IgA, IgM, IgD, and IgE. The two types of light chains are kappa and lambda.

Normally, many different plasma cells produce many different antibodies to protect us against a wide variety of infections.

With multiple myeloma, however, one abnormal plasma cell begins multiplying, creating a large group—or clone—of abnormal plasma cells.

These myeloma cells may produce large amounts of one abnormal immunoglobulin or part of an immunoglobulin.

You may hear this abnormal protein called an M-protein, monoclonal protein, paraprotein, or M-spike. Some forms of myeloma primarily produce abnormal free light chains rather than a complete immunoglobulin, and a small percentage produce little or no measurable monoclonal protein.

When Abnormal Plasma Cells Take Over

The problem isn't simply having an abnormal protein.

As myeloma cells multiply inside the bone marrow, they can interfere with the body's ability to produce healthy blood cells. This can contribute to anemia, weakened immunity, and sometimes low platelet counts.

Myeloma cells also interact with the surrounding bone marrow environment in ways that can damage bones. The abnormal proteins produced by myeloma cells can contribute to kidney damage in some patients.

This is why multiple myeloma can affect much more than the blood.

It can affect the bone marrow, bones, kidneys, immune system, and other parts of the body.

What About MGUS?

Finding a monoclonal protein does not automatically mean someone has multiple myeloma.

Some people have a condition called MGUS—monoclonal gammopathy of undetermined significance. MGUS involves a monoclonal protein or abnormal plasma-cell population but does not meet the criteria for active multiple myeloma.

Most people with MGUS will never develop multiple myeloma, although doctors generally monitor it because a small percentage of people progress each year.

There is also an intermediate condition called smoldering multiple myeloma, in which there are more abnormal plasma cells or monoclonal protein than with MGUS but no myeloma-defining event requiring treatment.

Understanding the Blood Helps Us Understand Myeloma

Multiple myeloma is often called a blood cancer, but much of the disease begins deep inside the bone marrow, where our blood cells are made.

Understanding the difference between blood plasma and plasma cells—and knowing what red cells, white cells, platelets, antibodies, and bone marrow actually do—makes it much easier to understand why myeloma can cause such a wide variety of symptoms and complications.

The more we understand what is supposed to happen inside healthy blood and bone marrow, the easier it becomes to understand what changes when myeloma enters the picture. As of February 2023, it is impossible to cure this cancer.