Bence Jones Proteins – Definition, Biology and Importance

What Does it Mean to Have Bence Jones Proteins in Your Urine?

What are Bence Jones proteins and why are they important?. Istockphoto.com/Stock Photo©Svisio

 

Bence-Jones proteins are essentially small pieces of antibodies that may be detected using a urine test, mainly to diagnose and monitor patients with multiple myeloma, a type of blood cancer. 

Bence-Jones Proteins in Multiple Myeloma

Multiple myeloma is a cancer that forms in a type of white blood cell called a plasma cell. Plasma cells are the cells that make antibodies to help you fight infections.

For a normal population of antibody-producing plasma cells, one could say that diversity is their business. They make all different types of antibody proteins.

Multiple myeloma is one of several diseases that can produce a "single clone of plasma cells." Think of a single clone as something akin to a crowd of identical twin cells. This crowd is not diverse. The single clone of cells generally makes the same antibody proteins.

Bence-Jones Proteins Are "M-Proteins"

In discussing Bence-Jones proteins, several other terms are often used, such as myeloma protein, M-proteins, paraproteins, free immunoglobulin light chains and the M-spike. These terms are all similar, but they aren't necessarily interchangeable. 

The 'M' in M-protein stands for monoclonal, meaning that the collection of proteins is from one clone of antibody-producing cells. These cells all produce the same antibodies, or antibody parts.

Bence-Jones Proteins Are Light Chains

Antibodies are what scientists call immunoglobulins - immune meaning they help fight disease, and globulin, meaning they are proteins. These immunoglobulins are usually quite large, but they are comprised of smaller units that are put together. Antibodies are actually comprised of of several smaller proteins, called heavy chains and light chains.

 

In the picture above, you can see a full antibody or immunoglobulin in the foreground, but each antibody is made up of a few parts. The blue parts are the "heavy chains" and the gold parts are the "light chains." In this picture, the gold light chains are what might become Bence-Jones proteins in a person with multiple myeloma or some other condition.

Bence-Jones proteins are essentially a special collection of these smaller pieces of an antibody (the light chains). The presence of light chains in such abundance in the urine is not normal. Normally, only a minute amount of light-chain protein can be detected in the urine. Light chains in the urine may develop for many different reasons, however, and not all of them are cancer.

Bence-Jones Proteins Are Monoclonal Light Chains

Now, in the case of Bence-Jones proteins, it is important to remember that these light chains are not just any old kind of light chain – they are monoclonal light chains.

Bence-Jones proteins, then, are...

  • monoclonal (come from one clone of cells)
  • monoclonal light chains (many copies of the same, smaller antibody-part)
  • found in urine and associated with a variety of conditions, including multiple myeloma.

Conditions in Which Bence-Jones Proteins May be Present

Bence-Jones proteins are particular types of M-proteins, and they are small enough to pass through your body's filtration system, the kidneys.

This means that, when these light chains occur in abundance, they will pass from your blood stream into your urine. There are several conditions in which Bence Jones proteins may be found in a person's urine, including the following:

  • Multiple myeloma - Multiple myeloma is a blood cancer in which there is an overproduction of plasma cells - cells that develop from B lymphocytes in the bone marrow. Plasma cells are the cells that make antibodies that protect us from certain viruses and bacteria. Between 50 and 80% of people with myeloma will have a urine test that is positive for these proteins.
  • Waldenström’s macroglobulinemia - Waldenstrom's macroglobulinemia is an uncommon cancer occurring in B cells (a type of white blood cell). B cells go through a process to become antibody-producing plasma cells. In this disease, the cancer occurs in the B cell, prior to the point at which it becomes a plasma cell; so, Waldenström’s macroglobulinemia is distinct from multiple myeloma, but the two conditions are, in some, ways similar, and both may result in Bence-Jones proteins.
  • MGUS - MGUS stands for monoclonal gammopathy of undetermined significance. This disease may be a precursor of multiple myeloma and involves an increase in the number of plasma cells, but none of the other symptoms associated with multiple myeloma.

Significance of Bence-Jones Proteins

Bence-Jones proteins are present in about two in three patients with multiple myeloma. Multiple myeloma is a blood cancer involving the excess production of plasma cells. Just as a lung cancer would have an excess of abnormal lung cancer cells, myeloma involves an excess of plasma cells.

Plasma cells are the cells that make antibodies to help us fight off disease. Cancerous plasma cells, however, don't make antibodies that help fight off disease, and instead, the excess plasma cells make excess antibodies which are all the same.

The excess of immunoglobulins in the body can become a problem from a number of different angles, one of which is kidney disease. Ordinarily, antibodies are too large to be filtered through the tubules in the kidneys. Bence-Jones proteins are small enough to enter the filtering units in the kidneys. In the kidneys, these proteins can build up and cause kidney problems. Some types of proteins are more likely to harm the kidneys in this way than others. There are also other consequences of excessive light chains that can affect different parts of the body.

If you have been diagnosed with an illness that results in excessive amounts of light chain proteins, your doctor will likely monitor you for related complications. One of the things that can happen with excessive light chains is called amyloid light-chain amyloidosis, whereby the light chains come together and form deposits of a substance called amyloid, which can cause damage in various organs.

Urine Test for Bence-Jones Proteins

The test for Bence-Jones proteins involves collecting your urine for 24 hours to check for evidence of the proteins. Bence-Jones proteins are named for Henry Bence Jones, a chemical pathologist who first discovered the unusual properties of these urine samples in the mid-1800s. There are two types of light chains - called kappa and lambda. The specific type of light chain can have clinical significance.

A Word from Verywell:

If you're newly diagnosed, take some time to learn about your disease and ask questions. Reach out for support from your friends and loved ones. And hang on to hope. The treatment of blood cancers has improved markedly in recent years, and new treatments are currently in clinical trials.

Sources:

Basile U, Gulli F, Torti E, et al. Evaluation of screening method for Bence Jones protein analysis. Clin Chem Lab Med. 2016;54(11):e331-e333.

Cook L, Macdonald DHC. Management of paraproteinaemia. Postgraduate Medical Journal. 2007;83(978):217-223.

Kyle, R., Larson, D., Therneau, T. et al. Clinical course of light chain smoldering multiple myeloma (idiopathic Bence Jones proteinuria): a retrospective cohort study. Lancet Haematology. 2014. 1(1):e28-36.

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